No / Ab initio calculations, combined with experimental studies on the anaerobic hydrolysis of phosphaalkynes under thermal and photochemical conditions suggest a potential, exogenous source of reduced oxidation state phosphorus for the early Earth.

Thesis (M.S.)--Michigan State University. Dept. of Fisheries and Wildlife, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references. Also issued in print.

No description available.

In order for an economy to survive and thrive it requires resources. Water is a resource that not only the economy is dependent on but also ecological and human communities. The deteriorated state of South African rivers suggests the intensive use of the country’s freshwater reserves by the population and industry. Such a source of freshwater is the Wonderfonteinspruit. It flows through an area that requires water for gold mining that has taken place in the area for more than 120 years. Furthermore, the Wonderfonteinspruit runs past communities such as Bekkersdal and eventually forms part of the source waters for the Boskop Dam, the main drinking water reservoir for Potchefstroom. Literature suggests that the Wonderfonteinspruit is impacted by anthropogenic activities, in particular impacts associated with both historical and current gold mining activities. The Wonderfonteinspruit has its origin in the Tudor Dam in Krugersdorp (now Mogale City), and then flows into Donaldson Dam from where it is piped in a 32 km long pipeline, before its confluence with the Mooi River which subsequently flows into the Boskop Dam. The study area specifically focuses on the Upper Wonderfonteinspruit from just downstream of the Donaldson Dam to just upstream of the dam. The study area was selected due to the close proximity of the Donaldson Dam to the community of Bekkersdal which formed the second part of the investigation for this thesis. Bekkersdal is primarily a mining community that has historically faced issues with sufficient land provision, housing, unemployment and service delivery. It is located in the Gauteng Province and falls under the jurisdiction of Westonaria Local Municipality. Recent protests by community members have occurred due to the lack of service delivery and inappropriate development of infrastructure with regards to water services. Due to the close proximity of Bekkersdal to the Wonderfonteinspruit (as it is situated on the border of the Donaldson Dam) the community provided an ideal study area to explore the use of the river by the community. In order to determine the relationship between the Wonderfonteinspruit and the community of Bekkersdal the study comprised two parts: during the first part of the study, the ecological state of the Wonderfonteinspruit was determined through the evaluation of the quality of water, sediment and biota within the river; while in the second part an assessment of Bekkersdal (both formal and informal sections) was undertaken through the use of questionnaires in order to determine past, current and future water use of both municipal water and water sourced from the Wonderfonteinspruit. The final outcomes of both the environmental and social assessments were then compared with national and international standards. Water quality assessment of the Wonderfonteinspruit was done by assessing the following: - in situ water quality parameters (such as pH, total dissolved solids and dissolved oxygen) - metal and ionic composition analysis of water samples using inductively coupled plasma mass spectrophotometry (ICP-MS) - nutrient loads using a spectrophotometer and Spectroquant® test kits - bacteriological quality by determining presence of total coliforms and faecal coliforms through the growth of bacterial cultures on M-ENDO and m-FC agar plates - the Physico-chemical Driver Assessment Index (PAI) was applied according to DWAF 2008 - statistical relevance between sites and results through principal component analysis (PCA) Finally, these results, where applicable, were compared to both national and international standards for human and ecological use. The results indicated that the water quality levels exceeded the guideline values of national and international standards for the following uses: drinking water, certain industrial activities, watering of certain livestock and crop types as well as aquaculture. It was also found that the water quality was acceptable for certain activities (e.g. recreation) only if precautions and further analysis are performed. The guideline values of national water quality standards for ecological status were also exceeded, while the PAI results indicated that the ecological category (EC) for the Wonderfonteinspruit is a D which indicates that the state of the water quality in terms of the ecology is fair. The sediment quality of the Wonderfonteinspruit was determined by ICP-MS. The metal composition of the sediment was compared to that of other rivers and the following indices were applied: enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and geo-accumulation index (Igeo). It was found that the sediment composition is comparable to that of other rivers impacted by gold mining and that uranium, cobalt and nickel enriched the sediment according to the indices. Biotic indicators that were assessed included fish, diatoms and invertebrates. The fish health assessment index (HAI) was applied to fish caught in the Donaldson Dam. The muscle tissue was also removed and its metal concentration was determined by ICP-MS. Thereafter, the edibility of the fish muscle tissue was determined and the following indices were applied: condition factor (CF), hepatosomatic index (HSI), gonadosomatic index (GSI) and spleen somatic index (SSI). The diatom community composition was assessed by applying the Biological Diatom Index (BDI), Specific Pollution Sensitivity Index (SPI) and the percentage pollution tolerant valves (%PTV). The Macroinvertebrate Response Assessment Index (MIRAI) was applied in order to determine the state of the macroinvertebrate community. The fish assessment indicated that arsenic contamination may negatively impact the health of consumers. Diatom indices indicated that the EC of the Wonderfonteinspruit is a D/E which indicates poor water quality; likewise, this is supported by the MIRAI results as the EC for MIRAI was a D which indicates that the river is largely modified. The investigation into the water use of the Bekkersdal community, with a special focus on the use of the Wonderfonteinspruit, was achieved through the use of questionnaires that were distributed in both formal and informal sections in Bekkersdal. The research forms part of a larger Integrative Multidisciplinary study and was given ethical clearance under the NRF Community Engagement Project (see Ethical Clearance: no. FH-BE-2013-0014. The National Research Fund (NRF) provided the funding for the research, the views expressed is that of the author and not those of the NRF. The aim of the questionnaire was to determine the following aspects in terms of the community of Bekkersdal: - Demographic details, such as language preference, employment status and age distribution. - Current water use practices . - Use of the Wonderfonteinspruit. - Future water use of the Wonderfonteinspruit. - Water quality perceptions of the Wonderfonteinspruit. - Field notes that included any relevant observations of the fieldworkers. The unemployment rate of the Bekkersdal community was found to be high (78.20%) and 86.40% of the residents are South African citizens. The community relies heavily on municipal provision of sources of water with 100% of the respondents indicating that it is their primary source of water. However, several issues were identified in terms of municipal water supply in the community. Some 10.14% of the residents indicated that they make regular use of the Wonderfonteinspruit (in particular the Donaldson Dam) most often for drinking water, laundry and washing of cars, etc. Regarding the state of the Wonderfonteinspruit, the overall viewpoint of the Bekkersdal community was that it is largely polluted with sewage, litter and mining waste. However, some 87.80% of the residents expressed their willingness to participate in environmental clean-up initiatives in their area. The link between the ecological state of the Wonderfonteinspruit and human health and wellbeing was explored through the use of spider diagrams where rank scores were assigned to both index results and human water quality use categories. These were compared and it was found that ecological indicators are more sensitive than human water quality use scores and therefore can aid in acting as early detection indicators of possible negative impacts on human health and wellbeing. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

In order for an economy to survive and thrive it requires resources. Water is a resource that not only the economy is dependent on but also ecological and human communities. The deteriorated state of South African rivers suggests the intensive use of the country’s freshwater reserves by the population and industry. Such a source of freshwater is the Wonderfonteinspruit. It flows through an area that requires water for gold mining that has taken place in the area for more than 120 years. Furthermore, the Wonderfonteinspruit runs past communities such as Bekkersdal and eventually forms part of the source waters for the Boskop Dam, the main drinking water reservoir for Potchefstroom. Literature suggests that the Wonderfonteinspruit is impacted by anthropogenic activities, in particular impacts associated with both historical and current gold mining activities. The Wonderfonteinspruit has its origin in the Tudor Dam in Krugersdorp (now Mogale City), and then flows into Donaldson Dam from where it is piped in a 32 km long pipeline, before its confluence with the Mooi River which subsequently flows into the Boskop Dam. The study area specifically focuses on the Upper Wonderfonteinspruit from just downstream of the Donaldson Dam to just upstream of the dam. The study area was selected due to the close proximity of the Donaldson Dam to the community of Bekkersdal which formed the second part of the investigation for this thesis. Bekkersdal is primarily a mining community that has historically faced issues with sufficient land provision, housing, unemployment and service delivery. It is located in the Gauteng Province and falls under the jurisdiction of Westonaria Local Municipality. Recent protests by community members have occurred due to the lack of service delivery and inappropriate development of infrastructure with regards to water services. Due to the close proximity of Bekkersdal to the Wonderfonteinspruit (as it is situated on the border of the Donaldson Dam) the community provided an ideal study area to explore the use of the river by the community. In order to determine the relationship between the Wonderfonteinspruit and the community of Bekkersdal the study comprised two parts: during the first part of the study, the ecological state of the Wonderfonteinspruit was determined through the evaluation of the quality of water, sediment and biota within the river; while in the second part an assessment of Bekkersdal (both formal and informal sections) was undertaken through the use of questionnaires in order to determine past, current and future water use of both municipal water and water sourced from the Wonderfonteinspruit. The final outcomes of both the environmental and social assessments were then compared with national and international standards. Water quality assessment of the Wonderfonteinspruit was done by assessing the following: - in situ water quality parameters (such as pH, total dissolved solids and dissolved oxygen) - metal and ionic composition analysis of water samples using inductively coupled plasma mass spectrophotometry (ICP-MS) - nutrient loads using a spectrophotometer and Spectroquant® test kits - bacteriological quality by determining presence of total coliforms and faecal coliforms through the growth of bacterial cultures on M-ENDO and m-FC agar plates - the Physico-chemical Driver Assessment Index (PAI) was applied according to DWAF 2008 - statistical relevance between sites and results through principal component analysis (PCA) Finally, these results, where applicable, were compared to both national and international standards for human and ecological use. The results indicated that the water quality levels exceeded the guideline values of national and international standards for the following uses: drinking water, certain industrial activities, watering of certain livestock and crop types as well as aquaculture. It was also found that the water quality was acceptable for certain activities (e.g. recreation) only if precautions and further analysis are performed. The guideline values of national water quality standards for ecological status were also exceeded, while the PAI results indicated that the ecological category (EC) for the Wonderfonteinspruit is a D which indicates that the state of the water quality in terms of the ecology is fair. The sediment quality of the Wonderfonteinspruit was determined by ICP-MS. The metal composition of the sediment was compared to that of other rivers and the following indices were applied: enrichment factor (EF), contamination factor (CF), pollution load index (PLI) and geo-accumulation index (Igeo). It was found that the sediment composition is comparable to that of other rivers impacted by gold mining and that uranium, cobalt and nickel enriched the sediment according to the indices. Biotic indicators that were assessed included fish, diatoms and invertebrates. The fish health assessment index (HAI) was applied to fish caught in the Donaldson Dam. The muscle tissue was also removed and its metal concentration was determined by ICP-MS. Thereafter, the edibility of the fish muscle tissue was determined and the following indices were applied: condition factor (CF), hepatosomatic index (HSI), gonadosomatic index (GSI) and spleen somatic index (SSI). The diatom community composition was assessed by applying the Biological Diatom Index (BDI), Specific Pollution Sensitivity Index (SPI) and the percentage pollution tolerant valves (%PTV). The Macroinvertebrate Response Assessment Index (MIRAI) was applied in order to determine the state of the macroinvertebrate community. The fish assessment indicated that arsenic contamination may negatively impact the health of consumers. Diatom indices indicated that the EC of the Wonderfonteinspruit is a D/E which indicates poor water quality; likewise, this is supported by the MIRAI results as the EC for MIRAI was a D which indicates that the river is largely modified. The investigation into the water use of the Bekkersdal community, with a special focus on the use of the Wonderfonteinspruit, was achieved through the use of questionnaires that were distributed in both formal and informal sections in Bekkersdal. The research forms part of a larger Integrative Multidisciplinary study and was given ethical clearance under the NRF Community Engagement Project (see Ethical Clearance: no. FH-BE-2013-0014. The National Research Fund (NRF) provided the funding for the research, the views expressed is that of the author and not those of the NRF. The aim of the questionnaire was to determine the following aspects in terms of the community of Bekkersdal: - Demographic details, such as language preference, employment status and age distribution. - Current water use practices . - Use of the Wonderfonteinspruit. - Future water use of the Wonderfonteinspruit. - Water quality perceptions of the Wonderfonteinspruit. - Field notes that included any relevant observations of the fieldworkers. The unemployment rate of the Bekkersdal community was found to be high (78.20%) and 86.40% of the residents are South African citizens. The community relies heavily on municipal provision of sources of water with 100% of the respondents indicating that it is their primary source of water. However, several issues were identified in terms of municipal water supply in the community. Some 10.14% of the residents indicated that they make regular use of the Wonderfonteinspruit (in particular the Donaldson Dam) most often for drinking water, laundry and washing of cars, etc. Regarding the state of the Wonderfonteinspruit, the overall viewpoint of the Bekkersdal community was that it is largely polluted with sewage, litter and mining waste. However, some 87.80% of the residents expressed their willingness to participate in environmental clean-up initiatives in their area. The link between the ecological state of the Wonderfonteinspruit and human health and wellbeing was explored through the use of spider diagrams where rank scores were assigned to both index results and human water quality use categories. These were compared and it was found that ecological indicators are more sensitive than human water quality use scores and therefore can aid in acting as early detection indicators of possible negative impacts on human health and wellbeing. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Variability is a universal, but poorly understood, property of ecosystems. A common belief that environmental variability has a destabilizing effect on species coexistence is being challenged by a growing body of theoretical research; variance in resource abundances may actually promote species coexistence. Here, I develop three models which give ecological conditions for coexistence on a single resource. The first considers a resource whose abundance varies seasonally. Coexistence may be possible if there is a tradeoff between foraging efficiency and maintenance efficiency. The first species can forage profitably on low resource abundances while the second uses dormancy to "travel" inexpensively between temporal periods of high resource abundance. The second considers a resource whose abundance varies spatially. Coexistence may be possible if there is a tradeoff between foraging efficiency and the cost of travel. The first species forages patches to a lower giving up density while the second can inexpensively travel between patches with high resource abundances. The third considers an environment in which foraging costs change seasonally. Coexistence may be possible if there is a tradeoff between the cost of foraging during different seasons. The species which is the most efficient forager changes seasonally. Because coexisting species often exhibit little apparent diet or habitat separation, seed-eating desert rodents offer a promising community for testing the three aforementioned mechanisms of coexistence. In a community of four granivorous rodents, (Perognathus amplus, Dipodomys merriami, Spermophilus tereticaudus, and Ammospermophilus harrisii), I used artificial seed patches to measure species and habitat specific foraging efficiencies. The third mechanism of coexistence appears to explain the presence of P. amplus, D. merriami, and S. tereticaudus in the community. Each enjoys a season during which it is the most efficient forager. The second mechanism of coexistence explains the presence of A. harrisii in the community. This species preferred to forage a large number of widely spaced patches to a high giving up density rather than foraging a few patches to a low giving up density.

>Magister Scientiae - MSc / Agricultural production is one of the most important sectors which provide food for the growing world population which is estimated to reach 9.7 billion by 2050, thus there is a need to produce more food. Climate change, on the other hand, is negatively affecting major global crops such as maize, sorghum, wheat and barley. Environmental factors such as salinity, drought, high temperatures and pathogens affect plant production by oxidatively damaging the physiological processes in plants, leading to plant death. Poor irrigation used to combat drought result in salinasation, which is estimated to affect 50% of arable land by 2050. Plants have developed several mechanisms that protect them against stress and these include overexpression of stress responsive genes and altered signal transduction to change the expression of stress responsive genes, among others. Cyclic 3’5’ guanosine monophosphate (cGMP), a second messenger that is synthesised by guanylyl cyclase (GC), transmit signals to various cellular functions in plants during plant development, growth and response to abiotic and biotic stresses. Arabidopsis thaliana nitric oxide guanylyl cyclase 1 (AtNOGC1) is a guanylyl cyclase which upon activation by nitric oxide (NO) leads to the production of more cGMP. Cyclic GMP further activates protein kinases, ion gated channels and phosphodiesterase which mediate response to various stresses. In this project the role of AtNOGC1 was investigated in response to abiotic and biotic stresses through analysis of its evolutionary relationships, promoter, gene expression and functional analysis via the viability assays in Escherichia coli (E.coli). Phylogenetic tree, exon-intron structure and conserved motifs were analysed using the Molecular Evolutionary Genetics Analysis (MEGA V.7), Gene Structure Display Server 2.0 (GSDS 2.0), and Multiple Expectation Maximisation for Motif Elicitation (MEME) tools respectively. AtNOGC1’s gene expression was analysed by the Real-Time Quantitative Reverse Transcription Polymerase Reaction (qRT-PCR), whereas functional analysis was carried out using the cell viability (liquid and spot) assays to determine its ability to confer stress tolerance to E. coli.

No description available.

The aims of this project were to: 1. further develop the evaluation systems of Westman (1986), Chapman and Underwood (2000) and Wilkins et al (2004) proposed for the assessment of restored ecosystems; and 2. use these developments to evaluate whether the revegetation of agricultural land on the Cumberland Plain, west of Sydney, NSW, has led to the re-establishment of a grassy woodland. The evaluation system developed in this Thesis was designed to compare three key ecosystem attributes. First, to assess how restoration was progressing, the species richness, composition and vegetation structure of abandoned pasture (starting point), was compared to that of restored vegetation of differing ages (putative mid points), and remnants (goal or end point). Refinements of the previous assessment models included formulation of predictions about native and exotic species richness and composition under the assumption that restoration was succeeding, and explicit testing of these predictions by planned comparisons and trajectory analysis of species composition. Second, the small-scale effects of planted tree canopies on species composition were assessed to test the hypothesis that native tree canopies facilitate the return of natives. Third, the effects of fire and neighbour removal on seedling emergence and establishment in pasture, restored vegetation and remnants were examined to explore what factors controlled germination and establishment. The results of this study indicate that to date, there has been a partial success of the restoration program at the study sites: while native species have returned unaided to restored sites, the trajectory of native species composition was not in the direction of remnants. There was however, increased species richness of exotic species detected underneath planted tree canopies. Patterns of seedling emergence observed in this study suggest that recruitment plays a role in the maintenance of the species composition found in restored vegetation, with seedling emergence dominated by exotics The evaluation methodology developed within this Thesis is a transparent and accurate way to measure ecological changes in vegetation that have occurred as a result of restoration.The restoration evaluation methodology further developed here will be useful to an industry that involves tree planting, landcare, revegetation and bush regeneration. It will complement guidelines provided by government and other sources that advise on practical aspects of revegetation and will be one of the few which have examined the success of revegetation in ecological terms that are founded on sound scientific basis. / Doctor of Philosophy (PhD)

The secondary productivity of communities is inherently influenced by the availability and quality of food resources. Movement of organic matter (OM) across landscapes can connect adjacent systems by providing subsidies of carbon and nutrients, implying that alterations of environments from their natural state may affect the productivity of neighboring food webs. The intact terrestrial and marine environments of Fiordland provide a setting to study linkages between the land and the sea. The first general objective of this study was to determine if large but nutritionally poor (nitrogen-poor, carbon-rich) inputs of forest litter support marine secondary production, and to identify pathways for incorporation of this material into upper trophic levels. Pools of marine and terrestrial OM had distinct values of [delta]�⁵N, [delta]��C and [delta]�⁴S, providing high power to estimate the relative use of these sources by the food webs of the fjord-head deltas. Deposit feeding invertebrates (e.g. Echinocardium cordatum, Pectinaria australis) directly assimilated plant detritus. Heterotrophic bacteria on the surface of the sediment assimilated forest litter and provided a potential food source for invertebrates. Chemoautotrophic bacteria fix CO₂ that originates from decomposing forest litter, thus providing an indirect pathway for incorporation of forest litter into the food webs. In the deep basins the strength of the flux of uptake by chemoautotrophic bacteria through the benthic food web into the upper trophic levels was demonstrated by hagfish (Eptatretus cirrhatus) obtaining 38-51% of their nutrition from these bacteria. The ability of a community to utilize discrete sources of OM relies on the presence of specific functional feeding guilds. Marine algae provide a highly nutritive (nitrogen-rich) food source for the fjord communities and fluxes of algae into food webs are facilitated by grazing invertebrates and filter feeders. The second general objective of this study was to determine how the effective loss of filter feeders from inner Doubtful Sound would alter the flux of marine-derived OM to the food webs of the delta communities. The low salinity environment imposed by the hydroelectric power station in Doubtful Sound caused a large reduction in the abundance of the infaunal bivalves Austrovenus stutchburyi and Paphies australis from delta habitats. Clams could tolerate periods of freshwater exposure of [less than or equal to]20 days duration, but the constant freshwater conditions in Doubtful Sound decreased survivorship. In 2004/05 the biomass of these species in inner Doubtful Sound (7.28 tonnes) was 29 times smaller than in Bradshaw Sound (214.12 tonnes). The associated loss of biodeposits (~91 tonnes(DW) yr⁻� in Bradshaw Sound vs. 1 tonne(DW) yr⁻� in inner Doubtful Sound) may have also altered the flux of nutritive OM to the infaunal community. The river delta communities in inner Doubtful Sound appear to have a higher reliance on forest litter than those in Bradshaw Sound, which is apparent as low values of [delta]�⁵N and [delta]��C for estuarine fish (Notolabrus celidotus, Hemerocoetes monopterygius), which act as integrators of the benthic community. This study demonstrates important linkages between terrestrial and coastal marine ecosystems and highlights the role of functional diversity in facilitating fluxes of organic material through food webs.