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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Microbial and physico-chemical assessment of on-site water supply systems /

Kolam, Joel. January 2003 (has links)
Thesis (M. Sc.) (Hons) -- University of Western Sydney, 2003. / "A thesis submitted in partial fulfilment of the requirements for the degree of Master of Science (Hons.), University of Western Sydney, Australia, Water Research Laboratory, Centre for Water & Environmental Technology." Includes bibliography : leaves 168 - 183 and appendices.
82

Biomonitoring in two contrasting catchments

Maseti, Pumza Penelope January 2006 (has links)
The introduction of instream biological monitoring to water resources management has been an increasing trend world-wide. This monitoring uses biological field assessments of instream biota such as macroinvertebrates, fish and riparian vegetation as an integrated and sensitive tool for diagnosing the condition of the ecosystems and assessing ecological impacts. Biomonitoring information has become an important component in the overall assessment of water resources and is used to drive and direct processes of decision-making and management of water resources. The River Health Programme (RHP) was initiated in South Africa to serve as a source of information regarding the ecological status of river systems, in order to support rational management of these natural resources. In this study, biomonitoring indices (SASS5 and FAII) were used to assess the present ecological status of two rivers located in contrasting catchments of the Eastern Cape. The first river is the Buffalo River located in an urban and industrialized catchment. The second river is the Inxu River draining a rural and afforested catchment. SASS5 was used successfully in both rivers and the results based on water quality and SASS5 indicated that most sites selected on the upper catchment of the Buffalo River have a fair water quality with most sites selected on the lower catchment having a poor water quality. The Inxu River sites (both upper and lower catchment) based on SASS5 and water quality results have a good to fair water quality. The majority of sites sampled on both rivers systems had very low FAII scores and fell within a critically modified water quality category. This result may be due to the fact that these rivers have low fish diversities (either low natural diversity or low diversity due to the presence of alien fish species), poor water quality or inadequate sampling methods. Observations from this study suggest that this index may not be suitable for rivers with low fish diversity. A fish index that is usable to all ecoregions of South Africa with minor adaptations to suit local conditions is still needed, as the present FAII index does not meet these requirements.
83

Aspects of the biological integrity of the Mutale, Mutshindudi and Tshinane rivers, Limpopo Province

Fourie, Albertus Jacobus 01 July 2014 (has links)
M.Sc. (Aquatic Health) / Aquatic ecosystems in rural South Africa have been impacted over many years by commercial and subsistence anthropogenic activities (DWAF, 2001). These impacts include commercial and subsistence farming, domestic use (e.g. washing of clothes, cars and bathing) and recreational use (e.g. fishing). In the northern parts of the Limpopo Province of South Africa (Vhembe District) the land use is primarily dominated by various agricultural activities and human settlements. Rivers in this region flow through mixed agricultural use, including commercial agriculture (tea and timber plantations) as well as subsistence farming and housing. Perennial rivers in this region include the Mutale, Mutshindudi and Tshinane rivers. These rivers are located in the Water Management Area 2 (WMA 2 Luvuvhu-Letaba) (Kleynhans, et al., 2007a). They are highland river systems, originating in the nearby Soutpansberg Mountain, and these rivers all form part of the larger drainage system of the Luvuvhu River, a tributary of the Limpopo River. The wetlands in the catchment of these rivers are also heavily utilised by the local communities (Working on Wetlands, 2013) used for grazing, sand mining and subsistence cultivation, thus providing a livelihood for the surrounding communities (SANBI, 2012). The aim of the study was to assess aspects of the biological integrity of the Mutale, Mutshindudi and Tshinane rivers. This study formed part of a larger study that included assessments of both abiotic and biotic aspects of these river systems. For this study, the focus was on assessing the fish community structure through the application of Fish Response Assessment Index (FRAI), riparian vegetation through the application of Vegetation Response Assessment Index (VEGRAI) and fish health aspects with special reference to liver and gonadal histopathology. Water quality parameters were found to be within the target water quality range for aquatic ecosystems. The results did however vary between upstream and downstream sampling sites. Similarly, compared to upstream sites, the FRAI showed the Mutale River to improve in fish community structure whereas the Tshinane and Mutshindudi rivers showed a decrease in the FRAI score. The VEGRAI results showed a decrease in EcoCondition in the Mutale and Mutshindudi rivers whereas the Tshinane indicated an increase. This can be attributed to land use change up to the edge of the river systems. Visual observation at the various study sites showed a definite localised impact of human activities on the beds and banks of many parts of the rivers. No histological alterations were identified in any of the gonadal or liver tissue of the Chiloglanis pretoriae (Shortspine suckermouth) (Van der Horst, 1931) and the fish were found to be in a healthy condition according to the selected parameters (gonads and livers) assessed. The fish community structure of the three rivers were found to be in a moderately to largely modified condition according to the ecological state categories calculated. However, the fish health assessment showed no histological alterations in the sampled fish. It is proposed that future studies investigate the influence of the domestic use of the rivers as well as attempt to quantify the impact of agriculture on the system.
84

Modelling payment systems for environmental services in the Mt Elgon ecosystem of Kenya

Kisaka, Lily January 2014 (has links)
Unsustainable patterns of consumption by humankind have increased the rate of change in the natural ecosystems and consequently the levels of stress experienced within the environment. Access to sufficient good quality water is essential and a requirement to meet a number of the Millennium Development Goals (MDGs). However, poor land management and untenable agricultural practices have become the main drivers of the declining watershed services. Upstream farmers often have little or no incentives to take these impacts into account in their decision-making process. Therefore, without investment in ensuring proper land management, the trend in watersheds degradation will continue. Payment for Environmental Services (PES) has emerged as an incentive–based tool that is expected to motivate farmers to improve their agricultural practices. PES is set up to facilitate the process whereby the beneficiaries of environmental services pay compensation to providers of environmental services for conserving the ecosystem. This tool has received increasing attention as a means of creating incentive measures for managing the ecosystem, addressing livelihood issues for the rural poor, and providing sustainable financing for protected areas. The Government of Kenya, as part of its efforts to improve water resource management, is considering use of economic incentive. However, there is insufficient information to guide policy making in that direction. Little is known about the farmers’ preferences for management schemes that will affect land use patterns, their willingness to accept compensation and the willingness of potential buyers to pay for the services. This study evaluates the willingness to accept and the willingness to pay for environmental services with a view to assessing the viability of a PES scheme for the Kuywa Watershed in particular, as well as the Mt. Elgon Ecosystem and other areas with similar conditions. The objectives of the study are threefold (i) to examine respondents preferences for management options for the provision of environmental services in the watershed of River Kuywa of Mt. Elgon Ecosystem; (ii) to evaluate households’ willingness to pay (WTP) and willingness to accept (WTA) payment for improved environmental services from the River Kuywa watershed; and (iii) to propose viable PES approaches for the management of the natural resource of the Kuywa watershed and the Mt. Elgon ecosystem in general. Using six land management attributes relevant to the local situation, the study applied the conjoint method to evaluate farmers’ preferences for management options for the provision of environmental service and assess farmers’ willingness to pay and willingness to accept payment for environmental services. To enable assessment of viability, an analysis was done of the institutional and legal framework within which the PES scheme would operate. Data were collected using literature review and document analysis, questionnaires, focus group discussions and key informant interviews. Results indicate that poor water quality was the most acute problem, followed by deforestation. Results from the conjoint models show that the length of commitment period and land size that is 40% or more of the total land holding influence the farmers’ rating of the management scenarios. The study found that a management contract that requires use of 20% of land holding for a period of 5 years, combined with a cash incentive, harvesting partially permitted, administered by a local NGO and requiring contribution of free labour for two days had the highest likelihood of being selected. The conjoint valuation exercise also came up with a WTA by farmers upstream of KSh. 7,080/= per year. The corresponding value downstream was KSh. 43/= per month over and above their regular water bill. In terms of the institutional and regulatory framework, Kenya has a wide range of policies, laws and regulation on water and other natural resources which provide an enabling environment for PES. With the decentralized institutional setup implemented in both the water sector and the agricultural sector, the institutional setting also provides an enabling environment for PES. With a positive WTA and WTP coupled with an enabling legal and institutional environment, the study concludes that PES is a viable environmental management tool for the Kuywa water shed and similar watersheds.
85

Determining water quality : development of a cell culture cytotoxicity assay

Humphries, Petro 19 September 2005 (has links)
Not only in South Africa, but also all over the world, pollution is threatening the quality of water resources. More than 100,000 chemicals are produced worldwide and some of these chemicals enter into the aquatic environment, posing a potential threat to humans, animals as well as other organisms. Therefore, determining the quality of water is of great importance. The testing of the toxicity of water samples are either based on a biological model or chemical model. In the biological model, organisms are utilized as indicators for toxicity of a particular sample, this sample may then be cytotoxic to the cells of the organism. In the chemical model the amount of a specific chemical present in water samples are predicted. Although, within the biological model there are many cytotoxicity screening assays (also called bioassays) that assess quality of water, there is a need for a fast, efficient and cost-effective cell culture system that may act as first screening procedure in a range of tests. Of particular importance in the context of this thesis, are bioassays that measure specific biochemical parameters, e.g. the Uridine uptake bioassay, MTT (3-(4,5¬dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide) assay and the bioluminescent assay. An important advantage of these assays are their sensitivity and the fact that the tests are principally based on cell mortality as a consequence of membrane damage or influence on cell metabolism. Researchers at the Highveld Biological Laboratory in South Africa have the past few years paid particular attention to the MTT assay, originally developed by Mosmann, and have modified this assay. In this thesis the adjusted method is referred to as the Modified Highveld Biological assay. There were, however, still a few adjustments to be made in order to use this modified method to its full potential. The Bioluminescent assay, also were thought to have potential to be modified as water quality screening test. Therefore, the hypotheses investigated in the current thesis were: • The original Mosmann MTT method can be modified successfully to provide a sensitive, reproducible mass screening method for determining chemical cytotoxicity and water quality, by using the K-562 cell line. • Sensitivity of the assay can be increased by utilizing a 3 phase medium cycle (Medium type 1-3) instead of the previously used single culture medium. • Furthermore, this cytotoxicity assay can be successfully utilized to determine whether any chemical solution or water sample is cytotoxic. Thus information was needed to determine whether cytotoxicity correlates with real life toxicity. This requires time-consuming epidemiological surveys unless results can be correlated with previous surveys. The research in this thesis attempted to indicate that the obtained cytotoxicity can be used to predict toxicity of a water sample, and that the cytotoxicity findings of this dissertation may indeed be meaningful. The culturing conditions of the Modified Highveld Biological MTT assay were modified successfully and could thus be utilized as the first assay in a battery of tests to determine overall cytotoxicity by utilising K¬652 cells in culture. Due to successful modification of the assay, this MTT assay now reduces assay duration, thereby saving important resources. An attempt was also made to optimise the Bioluminescent assay. This method is based on the fact that adenosine triphosphate (ATP) is present in all living cells. The method utilizes an enzyme, firefly luciferase, which catalyses the formation of light from ATP and luciferin. The emitted light intensity is linearly dependent on the ATP . concentration and is measured using a luminometer. The following problems were, however, identified that renders this method unsatisfactory as cytotoxicity indicator for water samples. • The luciferase enzyme is too sensitive to too many different substances used in the cell culture medium and in the preparation procedures of the cells (ions, salts etc.) which makes it less suited for usage for fast, effective testing of water toxicity. • This method will probably function better when luciferase can be carried into the cells or form part of the cells' genetic material. • We therefore suggest that, the Bioluminescent assay might possibly be a method to determine cytotoxicity, if the sensitivity of the luciferase enzyme could be further investigated. Thus it could be concluded that luminescence is not suitable for assaying complex mixtures because it is possible for unknown non~toxic agents, present in test samples, to interfere with the process of light emission (quenching). Lastly, known chemical solutions as well as unknown water samples were screened using the adjustments to the Modified Highveld Biological Method proposed in this thesis. The cytotoxicity of unknown water samples and chemical solutions were successfully determined and different cytotoxic effects were obtained, e.g. synergism, antagonism, additive effects and neutral effects. It was also possible to reduce or remove the cytotoxicity of certain water samples by applying pre~treatment with either Na2CO3 (removing possible toxic divalent and polyvalent metals) or SepPak cartridge clean up (removing organic toxicants). Results indicated that the method is very sensitive and can detect even low traces of toxicants. Thus, it can be concluded that the method was successfully adjusted to be useful as a first screening assay for toxicity analysis of a series of environmental water samples. / Dissertation (MSc (Anatomy))--University of Pretoria, 2006. / Anatomy / unrestricted
86

Application of Cultured Neuronal Networks for Use as Biological Sensors in Water Toxicology and Lipid Signaling.

Dian, Emese Emöke 08 1900 (has links)
This dissertation research explored the capabilities of neuronal networks grown on substrate integrated microelectrode arrays in vitro to be applied to toxicological research and lipid signaling. Chapter 1 details the effects of chlorine on neuronal network spontaneous electrical activity and pharmacological sensitivity. This study demonstrates that neuronal networks can maintain baseline spontaneous activity, and respond normally to pharmacological manipulations in the present of three times the chlorine present in drinking water. The findings suggest that neuronal networks may be used as biological sensors to monitor the quality of water and the presence of novel toxicants that cannot be detected by conventional sensors. Chapter 2 details the neuromodulatory effects of N-acylethanolamides (NAEs) on the spontaneous electrical activity of neuronal networks. NAEs are a group of lipids that can mimic the effects of marijuana and can be derived from a variety of plant sources including soy lecithin. The most prominent NAEs in soy lecithin, palmitoylethanolamide (PEA) and linoleoylethanolamide (LEA), were tested individually and were found to significantly inhibit neuronal spiking and bursting activity. These effects were potentiated by a mixture of NAEs as found in a HPLC enriched fraction from soy lecithin. Cannabinoid receptor-1 (CB1-R) antagonists and other cannabinoid pathway modulators indicated that the CB1-R was not directly involved in the effects of NAEs, but that enzymatic degradation and cellular uptake were more likely targets. The results demonstrate that neuronal networks may also be a viable platform for the elucidation of biochemical pathways and drug mechanisms of action.
87

Monitoring of heavy metals in the Bottelary River using Typha capensis and Phragmites australis

Ma, Ying January 2005 (has links)
Magister Scientiae (Biodiversity and Conservation Biology) / The aim of this study was to use plants to determine the degree of heavy metal contamination in water and sediments in order to effectively monitor and provide possible recommendation to improve the water quality in the aquatic ecosystem of the Bottelary River. / South Africa
88

Predicting water quality in bulk distribution systems

Rust, Tertius 12 1900 (has links)
Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: The increased water demand to be supplied by municipal water distribution systems, and subsequent increased storage period of reserve water, may have implications with regards to water ageing and subsequently may have an impact on health and safety. Current master planning design standards could have a negative effect on water residence time. The decay of the disinfectant potential is a function of the residence time in the distribution system. The objective of this study is to identify and measure existing systems to optimally increase water quality in a distribution system while supplying an increase in demand, dealing with the deterioration of pipe infrastructure and the introduction of alternative water sources. To do this, one must understand the dynamics of water networks and the parameters that affect water quality. The foundation of a water quality model is based on the construction of an accurate hydraulic model. To identify and measure these systems, one must understand the aspects of water purification and the techniques used to achieve water standards in a distribution system. These techniques and standards play a huge role in the prediction of water quality. In this paper the fundamentals and techniques used to determine and measure such a model are discussed. Consequently, additional design parameters to assess water quality must be incorporated into current master planning practice to optimally design water networks. These models are used to determine the appropriate levels of disinfectant at strategic locations in a system. To illustrate these design parameters and systems currently used in practice, a case study involving Umgeni Water (UW) and EThekwini municipality (EWS) was used to determine the most suitable disinfectant strategy for a municipality’s distribution system. Future scenarios and the impact of disinfectant mixing and increased residence time of the water in the system were also determined. The use of this water quality model in a distribution system will ultimately provide a sustainable platform for a risk monitoring procedure. / AFRIKAANSE OPSOMMING: Die verhoogde aanvraag na water in munisipale voorsieningstelsels, en die daaropvolgende verhoogde stoortydperk van reserwe water, kan implikasies inhou met betrekking tot water veroudering waarna dit ‘n impak op gesondheid en veiligheid kan hê. Huidige meesterbeplanning ontwerpstandaarde kan 'n noemenswaardige uitwerking op water retensietyd hê, veral omdat chloor se vervaltyd op sy beurt 'n funksie van water retensietyd is. Die doel van hierdie studie is om 'n prosedure te identifiseer om watergehalte optimaal te verhoog in 'n waterverspreidingstelsel, terwyl die toename in water aanvraag voortduur. Om dit te kan doen moet die dinamika van water netwerke en die parameters wat die gehalte van water beïnvloed, bestudeer word. Die opstel van 'n waterkwaliteit model is gebaseer op die bou van 'n akkurate hidrouliese model. Om uiteindelik die ontwerp van 'n waterkwaliteit oplossing suksevol uit te voer, moet 'n mens al die aspekte van watersuiwering en die tegnieke wat gebruik word om waterstandaarde te handhaaf in 'n verspreidingstelsel verstaan. In hierdie verslag word die beginsels en tegnieke wat gebruik word om so 'n model op te stel, bespreek. Bykomende waterkwaliteit ontwerpparameters moet by huidige meesterbeplanning gevoeg word om waternetwerke optimaal te ontwerp. Hierdie modelle word gebruik om die geskikte vlakke van ontsmettingsmiddel op strategiese plekke in 'n stelsel te bepaal. 'n Gevallestudie van Umgeni Water (UW) en eThekwini-munisipaliteit (EWS) is gebruik om die mees geskikte ontsmettingsmiddel strategie vir 'n munisipaliteit se verspreiding te illustreer. Toekomstige scenario's en die impak van ontsmettingsmiddelvermenging en verhoogde retensietyd van die water in die stelsel sal ook bepaal kan word. Die gebruik van hierdie gehalte-watermodel in 'n verspreidingstelsel sal uiteindelik 'n volhoubare platform vir 'n risiko moniteringstelsel inhou.
89

The Ascidian Styela plicata As a Potential Bioremediator of the Brown Tide Pelagophytes Aureoumbra lagunensis and Aureococcus anophagefferens

Unknown Date (has links)
A brown tide bloom of the pelagophyte Aureoumbra lagunensis caused significant impacts to north Indian River Lagoon (IRL) in 2012-2013, including seagrass die-offs, fish kills, and reduced growth and grazing of ecologically important bivalves. There is potential for another pelagophyte, Aureococcus anophagefferens, to expand into this system. Filtration rates (FR) of the pleated tunicate Styela plicata exposed to Aureoumbra lagunensis and Aureococcus anophagefferens were measured against exposure to a control alga (Tisochrysis lutea) in order to determine its potential use as a bioremediator against these harmful algal blooms (HABs). In addition, whether S. plicata might serve as a vector of HABs was studied by culturing fecal deposits. Short-term exposure to HABs significantly reduced FR, whereas long-term exposure indicates comparable cell removal compared to the control. Vector potential of S. plicata was inconclusive. Results warrant further research to determine whether S. plicata can acclimate or respond to HAB conditions over time. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection
90

Assessment of the impact of anthropogenic activities on water quality, biodiversity and livelihood in Lake Tana, Northwestern Ethiopia

Tamiru, Sisay Misganaw 09 1900 (has links)
Lake Tana is a biodiversity and natural reservoir for fresh water supply contributing significantly to the economy of Ethiopia and downstream recipient countries, namely: Sudan and Egypt. The Lake Tana Ecosystem provides a variety of goods and services such as: provisioning, regulating, amenity and supporting services. These services are affected by high human activities which threaten the water quality and biodiversity of the lake. Hence, this study aims to assess the impact of human activities on water quality, biodiversity and livelihood of Lake Tana and its shore sides.To assess the impact of anthropogenic activities of Lake Tana; physicochemical parameters, macroinvertebrates, macrophytes and livelihood of the Lake side communities were collected in the year 2014/2015 during dry and wet seasons for 11 sampling sites as indicated in Figure 1.1 and Table 1.1. The variations of physicochemical, metals and bacterial parameters were investigated. The overall water quality parameters (mean analytical results) of Lake Tana were found to be: Temp (Temperature)23.0OC, pH 7.5, EC (Electrical conductivity)180.1 μS/cm, BOD5 (Biological oxygen demand in 5 days)37.3 mg/l, COD (Chemical oxygen demand)316.5 mg/l, TSS 0.3 mg/l, TDS 93.1 mg/l, SO4 2- 11.0 mg/l, PO4 3- 42.4 mg/l, Cr (0.08 mg/l), (Mn (0.01 mg/l), E. Coli (13.4 Cell/ml), F. Coliform (82.5 Cell/ml), T. Coliform (113.0 Cell/ml), etc. These parameters did not show significant variation among the sites but were significantly different between wet and dry seasons (P<0.05). The highest concentration values were recorded during the wet season. However, most of the parameters under investigation were within the Ethiopian EPA (Environmental protection agency) permissible range except PO4 3-, S2-, E. Coli (Cell/ml), F. Coliform (Cell/ml) and T. Coliform (Cell/ml). Based on the analysis of the water quality index (WQI), Lake Tana water was unfit for drinking purpose and needs treatment. For theMacroinvertebrates analysis, a total number of 629 macroinvertebrate individuals are belonging to 9 orders and 38 families were found. In the study year impacted areas number of identified macroinvertebrates were 478 (76%); of this, 233 (37%) were in the wet season and 245 (39%) in the dry season and the total number of individuals identified in the reference area was 151 (24% of the total) in the wet season 61 (9.7%) and in the dry season 90 (14.3%) individuals. The diversity was more in the dry season. The dominant orders were Odonata (156 individuals), Coleoptera (153 individuals) and Hemiptera (141 individuals). The literature indicated that the presence of more Odonata, Coleptera and Hemipteran larvae is an indication of water quality deterioration due to pollution. From the collected samples, the total number of tolerant individuals was 303 (48.2%) and facultative individuals were 243 (38.7%) while intolerant individuals were 80 (12.7%). Most of the taxa (48.2%) had tolerance scores ranging from 7 to 10. The analysis of different forms of indices showed poor water quality. The water quality of Lake Tana was also determined by developing the LTMI (Lake Tana Metric Index). The index indicated the impairment levels of the study sites. Seven of the sites were in the category of poor (disturbed) and the other three were very poor (highly disturbed). The study on macrophytes recorded 43 species and 18 families during the two seasons (wet and dry), throughout the study year. 2687 individual macrophytes were collected; 1756 in the wet season and 931 in the dry season. Poaceae (15 species) with abundance mean 215.40 ± 421.7 was the most dominant family, followed by Cyperaceae (5 species) 35.40 ± 68.3. Sacciolepis africana was the dominant macrophyte species in Lake Tana. But in the study area Ambobahir, the dominant species was Cyperus papyrus while the Megech study area was invaded by the nuisance exotic weed Eichhornia crassipes. In the present study, the low macrophyte diversity values of Shannon Wiener index (2.90), Simpson Diversity Index (1-D) (0.90), Simpson Dominance Index (D) (0.10), Margalef’s index (M’) richness index (5.32) and Evenness Index (E) (0.77) throughout the study year indicate moderate water quality status while the presence of certain bio-indicator species like Eichhornia, Potamogeton and Cyperus in the lake also confirm pollution. Because of the effect of human activities on water quality and biodiversity, the livelihood of the riparian community is affected indirectly. Hence, to recommend mitigation and remediation actions, this study also focused on the assessment of the change of livelihoods of people living in the study area using qualitative research methods (key informant interview, focus group discussion (FGD), observations, published and unpublished materials and photographes). Lake Tana is a home to different flora and fauna including endemic species. The flora such as macrophytes and forest resources are used mainly for traditional medicine, fuel wood, rope, pole, habitat for birds, animal feed, etc. and the fauna includes fish, hippos, crocodiles, invertebrates, etc. Further, the Lake Tana area is a good habitat for indigenous cattle breeds (Fogera breed) and field crops gene center. The major resources around Lake Tana are land (the major source of livelihood), vegetation resources (macrophytes and forest resources), wildlife resources (fish, the other important source of livelihood) and cultural landscapes (churches and monasteries). Lake Tana is exposed to a set of interrelated environmental problems induced by human influence such as deforestation, erosion, sedimentation, water level reduction, erratic rainfall, flood, and competition for water resources, pollution and introduction of alien species. The causes to these problems were overgrazing, farmland expansion, cultivation of marginal lands (shorelines), encroachment of communal land, pollution and vegetation removal to meet demand for food and fuel wood. It is observed that alteration of Lake Tana and its fringe wetlands has affected the whole dynamics of the Lake’s ecosystem and the livelihood of the surrounding community. Ecosystem components are interlinked; hence correlation analysis was done between physicochemical parameters and macroinvertebrates of Lake Tana. Thus, correlations among many of the physicochemical parameters and macroinvertebrates families have been observed. To mention some of the correlations, the changes in the physical, chemical and biological characteristic of the lake affected the aquatic life forms and significantly affect economic activities that the lake supports. The RDA(Canonical redundency analysis) ordination of the species-environmental variable association indicated that pH, Cd, Pb and SO42- and Velidae, Chironomidae, Physidae, Gerridae, Corixidae, Dytiscidae, Caenidae, Coenogrionidae Simuliidae and Psephenidae were negatively correlated while Mussidae positively correlated with these environmental variables. This study concludes that the main threat to aquatic ecosystems in Lake Tana arises from agricultural activities, urbanization and industrialization that deteriorated water quality and biodiversity. Thus, it is recommended that proper management of Lake Tana should be put in place to prevent further deterioration of water quality and biodiversity of the lake for its sustainable development. / Environmental Sciences / Ph. D. (Environmental Science)

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