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Item Acoustic characteristics of major fish species of Lake Victoria with a view to refining standing stock estimate(University of Dar es Salaam,, 2012) Kayanda, Robert JeremiahRecent expansion of Lake Victoria fisheries has highlighted the need for high quality scientific advice in support of management. This study aims to address some key scientific components in the management process, paying particular attention to Nile perch, an introduced species, and dagaa. Central to the study has been acoustic estimation of standing stock, an essential component of which is the target strength (TS). Around 90% of the acoustic backscatter contributing to the fish TS is due to the swim bladder, a gas filled organ whose volume varies with fish size and vertical movement. Two approaches are used to estimate swim bladder volume and the results used to model TS for comparison with in situ studies from which the following revised TS to length relationships have been developed:TS70 = 32.11 *Log(TL)-86.97 at 70 kHz and TS120 = 30.15*Log(TL)-84.14 at 120 kHz. Concurrent hydrographic sampling during acoustic surveys provided data to investigate variation due to temperature, dissolved oxygen and chlorophyll-# on fish distribution vertically over all of the lake and including seasonal variation. This has been extended by using acoustic survey data to categorise lakebed substrate types. The results from the acoustic surveys along with data direct from the fisheries have been incorporated into Cadima model. The results show that Nile perch is under intense fishing pressure with biomass reduced and current catches above MSY. In contrast the ‘dagaa’ fishery appears below MSY and potentially has scope for expansion. Suggestions for improved management are given which if implemented would ensure a bright future for the fisheries. An emphasis is put on the integration of the co-management principles at all levels and increasing the sense of ownership by fishing communities around the lake.Item Age, growth reproductive biology and fishery of rastrelliger Kanagurta (Clivier, 1817) in Zanzibar, East Africa(University of Dar es Salaam, 2000) Jiddawi, Narriman S.A total of over 4500 specimens of Rastrelliger kanagurta (Scombridae) were obtained from two of Zanzibar's most important landing sites for small pelagics, ZAFICO and Malindi Jetty and were used to investigate aspects of their reproductive biology and growth in Zanzibar waters. The largest female and male R. kanagurta recorded from the purse seine fishery were 26.4 cm (183.9 g) and 24.9 cm (157 g) respectively, whereas the smallest fish were 12 cm (15.4 g) for females and 12.5 (17.5 g) for males. The largest R. kanagurta, however, from a different fishery was 36 cm (501 g) female fish. The smallest R. kanagurta during the whole study period had a length of 9.3 cm with a weight of 7.5 g (O-group). Spawning was found to occur throughout the year with two major peaks occurring in March/ April and September/October. Two recruitment peaks were also observed probably resulting from these two spawning peaks six months later. The gonad somatic index was found to be a good indicator in determining the spawning season with higher values coinciding with the period when the fish were about to spawn. The monthly size progression of the ova is illustrated by frequency polygons, which indicate that the eggs are shed in batches. Sex ratio was 1:1 in all sizes in all the months except in the bigger sizes above 22 cm, where females were slightly more than males. Fecundity was found to relate to size and bigger females produced more eggs with the average number of eggs in one ovary ranging from 41,883 to 184,328. The mean size at which 50% of the fish mature was found to be 19 cm for males and 20 cm for females. The length-weight relationship did not show any significant difference between the sexes throughout the year. The "b" values for males and females were 3.2 and 3.0 respectively. Age was determined using the indirect length frequency method ELEFAN 1 sub routine from the FiSAT software. The fish was found to be short-lived about 2-3 years and very rarely reached 5 to 6 years. Direct ageing with otolith and scales was also tried and these were observed to possess circuli, which in otoliths were found to increase in number with the size of fish. The process of observing scales and otolith was tedious and difficult and further studies are required on this aspect, but the work indicated that daily growth ring analysis might be possible. The ELEFAN 1 analysis was also used to estimate growth rate. The parameters of the Von Bertalanffy growth curve were found to be 36 cm for L¥ and 0.63 for K. The ELEFAN 1 analysis in conjunction with Pauly's method for calculation of instantaneous natural mortality rate indicated an M of 1.29. Catch curve analysis provided an estimate of instantaneous total mortality rate Z of 3.79. Instantaneous fishing mortality rate was 1.63 (Z-M). The fishery operates throughout the year with the greatest catch during the North East Monsoon (November to March). The fishery starts on the 17th or 18th day from the sighting of the new moon to the 8th or 9th of the next new moon. This period is locally known as the "Bamvua". The surplus production analysis indicated that fishing effort has exceeded the effort which would provide maximum sustainable yield. Current effort should be reduced by 50% to maximize productivity and avoid further declines in landings.Item Anaerobic degradation of cereal residues by a rumen derived process(University of Dar es Salaam, 1990) Kivaisi, Amelia KajumuloThe conversion of lignocelluloses into biogas in a Rumen Derived Anaerobic Digestion (RUBAD) process was studied. Anaerobic degradation of lignocelluloses in conventional digesters is a slow process mainly due to low enzymatic activity present and lignin protects the degradable polysaccharides against enzymatic attack. On the contrary, the rumen degrades lignocelluloses efficiently because ruminants employ many highly cellulolytic microbial species. Hence the RUDAD-process has a potential to degrade lignocelluloses. However, lignin has been shown to inhibit rumen microorganisms in vitro. To examine the performance of rumen microorganisms in degrading lignocelluloses, various materials with lignin contents between 0 and 34% of total solids were tested in batch cultures and in the RUDAD-process. An increase in lignin content resulted in decrease of degradability. The effects of externally added lignin or lignin monomeres on in vitro degradation of filter paper cellulose by rumen micro-organisms and on their cellulose activity were studied in batch cultures. Addition of these compounds in concentrations comparable to natural conditions showed minor inhibitory effects. It appeared that the decrease of degradability with increasing lignin content was caused by lignin forming a physical barrier to enzymatic attack on the degradable polysaccharides. Rumen micro-organisms were further tested for degrading various cereal residues in a one-phase process. Under standard rumen conditions, and loading rates varying between 9.8g of volatile solids per litre per day, total fibre degradation efficiencies were in the 42-57% range irrespective of the loading rates applied. Optimum degradation of barley straw fibre (16% lignin) was obtained under conditions similar to those found in the rumen in vitro. In all of the experiments 40-60% loss in lignin was observed based on fibre analysis. The degradation efficiency of the straw in a two-phase process was 50%. The fermentation products of the first phase were converted to biogas in the second phase. The two-phase process was demonstrated to be stable for over three months with straw as the sole substrate for anaerobic digestion. To check if lignin was solubilized during the degradation of lignocelluloses the presence of soluble lignin derived compounds in the reactors fed barley straw was determined by Ultraviolet Spectral Characteristics and Pyrolysis Mass Spectrometry. Most of these compounds were shown to be released from the cell walls by the action of rumen micro-organisms. Determination of the association between rumen ciliates and methanogenic bacteria on the bias of coenzyme F42O-2 was attempted. The ease of extracting and quantifying the coenzyme makes the assay a much better method of assessing the extent of association than direct microscopically enumeration of methanogens.Item The analysis and performance improvement of optical fibre communication systems at high data rates.(University of Dar es Salaam, 1996) Kundaeli, Herald NkyaOptical fibres have been increasingly used in communication due to their higher capacity, higher speed and higher reliability over other means of communication. Unfortunately, efforts to maximize their utilization have been hampered by a number of limitations, the most significant among them being dispersion in the fibres. A lot of efforts have therefore been expended in attempting to reduce the effects of dispersion. Among the methods used are optical phase conjugation, pulse shaping, and both electrical and optical equalization. In this research, dispersion-related distortions in pulses were first investigated, and followed later by attempts to reduce the distortions by pulse shaping. A mathematical model for dispersion-related pulse distortions in Gaussian-shaped pulses was developed. This was extended to take into account both the finite line width and the chirp of the laser. The results showed the expected pulse broadening associated with second-order dispersion and the separation of single pulses into multiple pulses associated with third-order dispersion. They also showed the presence of interference pulses produced when any two pulses interfered with one another. For more clarity on pulse distortion, the shapes of the interference pulses rather than their spectral content was analyzed, an approach which differs from work reported elsewhere. The amplitude of the interference pulses was found to be higher in dispersive fibres than in non-dispersive ones, and to decrease with the width of the source spectrum. It was also found to decrease as the distance between the interfering pulses increased. The interference pulses were found to be positioned midway between the interfering pulses when third-order dispersion was negligible, and to be positioned at the later occurring interfering pulses when the third-order dispersion increased. A mathematical model for dispersion-related pulse distortions was developed for square-shaped pulses. The distortions in the pulses were found to follow the same pattern as that observed for the Gaussian-shaped pulses with two exceptions. Firstly, there was less distortion outside the pulse widths of the square-shaped pulses because of their time-limited nature, and no interference pulses were found to be present when the fibre was non-dispersive. Secondly, the interference pulses were found to be positioned at the same positions as the interfering pulses when third-order dispersion was negligible, but they were found to be positioned at the same positions as the later occurring interfering pulses with increased third-order dispersion. The results for the square-shaped pulses are unique because no previous references were found on the analysis of such pulses. Attempts were made to investigate the pulse distortions caused by the focusing elements at the junctions of the communication lines. In this case, a new tool was developed by adapting tools developed for use in general optics to the analysis of pulse distortions in optical fibre communication. By employing this tool, the pulses were found to be distorted when the transmitting or receiving components at the junctions were spaced away from the focal point of the focusing elements, and they were also found to be distorted when the focusing elements were dispersive. The distortions were found to be greatly reduced when an optimized focusing system was used, showing that pulse distortion could be reduced by using well designed focusing elements, and by positioning the receiving components at the focal points of the focusing systems. Attempts were also made to find out if pulse distortions could be reduced by choosing appropriate shapes for the transmitted pulses. In the first attempt, data pulses were constructed from smaller pulses (mini-pulses) whose amplitudes were chosen so as to give the desired shapes to the data pulses. The pulses were then analyzed using the square-shaped pulse model. This attempt, for which the idea of using mini-pulses was new, did not produce improved results. The second attempt was based on a model developed from the laser rate equations, the Gaussian-shaped and the square-shaped pulse models. With this model, it was possible to use the laser rate equations to analyze the effects of second-order dispersion and third-order dispersion separately for the first time. Results from this attempt showed significant improvements when trapezoidal pulses with a pedestal on the leading edge were used. The developed models and tools have been used to propose new methods of combating dispersion-related pulse distortions, and they have also opened room for future work on such distortions.Item Analysis of met-ocean processes in relation to changes in large scale climatic systems in Tanzania and the western Indian Ocean(University of Dar es Salaam, 2014) Mahongo, Shigalla BassandaThe recent changes in world climate have highlighted the need for a proper understanding of the factors that influence changes in met-ocean processes in Tanzania and the western Indian Ocean. The region is unique in that these changes have generally not been fluctuating in consistence with the global change processes, thus posing a notable scientific challenge. This thesis addresses how these processes have been changing overtime in the region, and how they are associated with the large scale climatic phenomena. The thesis also discerns the oscillatory patterns of the met-ocean parameters, and investigates their potential for prediction. The study is implemented through wavelet and spectral analyses, multivariate linear regressions and other statistical tools, while prediction is carried out through artificial intelligence and linear time series modelling. Key findings of this study include the revelation of significant warming trends of surface air temperature, general strengthening of winds, decline in rainfall, and the presence of a quasi-22-year cycle on the low frequency timescales of winds and sea level, which mimic the Hale solar cycle. The influence of the 22-year rhythm is larger in amplitude than those due to large scale climatic systems. At the Island of Zanzibar for instance, the short sea level record of 1984-2004 largely resonated with the 22-year rhythm thus leading to a spurious negative trend. However, the relationship between solar activity and met-ocean processes is complex and varies with time and space such that this pattern cannot be generalized for other locations in the region. This thesis has also revealed that neural networks and state-of-the-art time series models are capable of making excellent predictions of sea surface temperature, thus providing potential for prediction of other met-ocean parameters. Determination of low frequency oscillations in met-ocean parameters is dependent on the length of the record, with about 100 years of data being needed for any conclusive evidence on trends in climate. Although ocean monitoring is currently possible through satellites, instrumental monitoring is still needed for calibration of the satellite sensors. Continued in-situ and satellite monitoring of the met-ocean parameters is therefore essential for a better understanding of the processes, permitting sound prediction and enabling proper planning, adaptation and resilience.Item Analysis of the interaction between cassava brown streak ipomoviruses and selected cassava varieties in Tanzania(University of Dar es Salaam, 2019) Shirima, Rudolph RufiniCassava (manihot esculentaCrantz)is an important staple food crop in sub-saharan Africa, but its production is adversely hampered by viral diseases. The most important is cassava brown streak diseases (CBSD) Caused by cassava brown streak ipomoviruses (CBSIs) {Genus Ipomovirus, family, Potyviridae; cassava brown streak virus (CBSV) and Ugandan cassava brown streak virus (UCBSV).CBSD causes significant yield losses In East and Central Africa .This study aimed at analysing the interaction between CBSIs and their cassava host under diverse agro-ecological conditions and CBSD pressure In Tanzania to contribute to CBSD management strategies. In this study,(1)aprotocol for absolute quantification of CBSIs was optimized and validated (2)The genetic diversity of CBSIs and virus titre were determined in selected cassava varieties(3) cassava degeneration due to recycling of planting material was assessedunder high CBSIs inoculum condition in Bagamoyo , Tanzania during the short (vuli) and long (masika)rainy season (4)The response of elite cassava varieties to CBSIs under diversearo-ecological environments in Tanzania was evaluated. Varieties differed significantly in virus titre whereas higher virus titres were observed in root than in leaves. Younger crops (2MAP) Had higher virus titre in leaves than old crops (12MAP).CBSIs were equally distributed across agro-ecological sites. Significantly higher, B. tabaciabundance, CBSD incidences and reduction in root yield were observed in Vuli than in Masika suggesting higher degeneration rates in the vuli.Cassava varieties respondedsignificantlydifferent across agro-ecological zoneswith the greatest impacts of CBSD in north-western Tanzania. Results of this study will be useful in informing breeding strategies. Evaluating cassava for release and in commercial seed production in designing new cassava .Item Anti HIV, Immunomodulatory and antimicrobial activities of extracts of some plant species from Bukoba, Tanzania(University of Dar es Salaam, 2018) Mpinda, Cyprian BedaCertain plant species are used in traditional medicines to treat illnesses including those caused by highly infectious agents like HIV. In this study, aqueous and ethyl acetate extracts from eight plant species were screened against inhibition of HIV-1 protease, cytotoxicity, antioxidant activity, immune-modulating effects and activity against opportunistic infections. The inhibitory effect of the extracts against HIV-1 protease was tested using a fluorogenic assay. Cytotoxicity was assessed using the 2,3-bis-(2-methoxy-4-nitro-5-Sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) viability assay and confirmed by using real time cell electronic sensing technology (RT-CES). Antioxidant activity was measured using 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and cupric reducing antioxidant capacity (CUPRAC) assays. Inflammatory activities were measured by using the nitric oxide colorimetric assay while antimicrobial activities were assessed using disc diffusion assay. Three out of eight aqueous extracts showed HIV protease inhibition with IC50 values ranging between 22.4 and 32.8 µg/ml. Aqueous extracts showed no cytotoxicity whereas only two ethyl acetate extracts were cytotoxic with CC50 values of 30.6 and 52.2 µg/ml. The antioxidant activity was higher for water extracts with EC50 values ranging from 1.894 to 23.46 µg/ml. The nitric oxide (NO) assay revealed that some aqueous extracts supported the production of the inflammatory mediator, NO, from peripheral blood mononuclear cells while others reduced or inhibited its production. Extracts were found to have moderate antimicrobial activities with MICs ranging from 3.1 to 100 mg/ml. Preliminary phytochemical screening of the aqueous extracts showed the presence of saponins, tannins and alkaloids. Findings of this study support the regular usage of these plant species for medical purposes against HIV/AIDS. Further studies, especially testing more HIV-1 enzymes, in vivo studies and characterization of the active chemical compounds responsible for the observed activity are recommended.Item Antimicrobial, antiviral, larvicidal and other secondary metabolites from Tanzanian annonaceae species(University of Dar es Salaam, 2010) Samwel, StephenThis Thesis reports the results from investigations of five Tanzanian Annonaceae species in which the leaves of Toussaintia orientalis Verdc. yielded the new indolidinoids toussaintine A - C, the N-cinnamoyl hydrobenzofuranoid toussaintine D, the N-cinnamoyl acetoxymethylcyclohexenoid toussaintine E, the β-glucoglycerylaminooctenyl adipate named orientalin, and the glycoflavonoid 3'-dehydroxyquercitrin. The leaves of another Toussaintia species, T. patriciae Q. Luke & Deroin which was only recently described, gave ursolic acid, its derivatives 19α,23-dihydroxyursolic acid and 29-hydroxyursolic acid, together with ethyl gallate. The stem and root barks of Artabotrys modestus Verdc. yielded the new diphenylpentanoid artabotrinone, aminotriketide diterpenoid artabotramide and known metabolites. The new N-methoxyoxoaporphinoid artamonteirine and the naphthalene derivative artamonterone were obtained from the stem bark of A. monteiroae Oliv. The leaves, stem and root barks of the new Annonaceae species Mwasumbia alba Couvreur & D.M. Johnson yielded the cyclitol quebrachitol, together with polycarpol. The structures of the isolated compounds were established based on analysis of their spectroscopic data, some structures also being further confirmed by X-ray diffraction analysis. Some of the isolated compounds exhibited in vitro antimicrobial potency against Staphylococcus aureus, Escherichia coli, Candida albicans and Cryptococcus neoformans, in ovo antiviral efficacy against Infectious Bursal Disease Virus and Newcastle Disease Virus, and larvicidal activity against Anopheles gambiae s.s Giles mosquito larvae. These results demonstrated some of the compounds to be potential leads for drug development.Item Aquaculture of nile tilapia (oreochromis niloticus linnaeus, 1758) with an assessment of its economic benefits in the lake Victoria basin, Tanzania(University of Dar es Salaam, 2013) Shoko, Amon PaulFish stocks in Lake Victoria have drastically declined while the demand for fish has exponentially increased, leading into inadequacy of fish. Aquaculture has the potential of bridging the widening gap created by the increasing demand. Despite the enormous potential for aquaculture development in the Basin, this sub-sector is still underdeveloped. This thesis examined the aquaculture of Nile tilapia (Oreochromis niloticus) and assessed its economic benefits in the Basin. Assessment on fish pond performance suggests that, despite low fish yield due to poor pond management, aquaculture offers an opportunity for increased productivity. Investigations on diurnal dynamics of water quality parameters showed that dissolved oxygen and un-ionized ammonia were beyond the acceptable limits for fish growth suggesting a need for frequent water quality monitoring in ponds. The effects of integrating fish farming with vegetables on fish growth, yields and economic benefits revealed higher performance from integrated than from non-integrated system, pointing to the importance of integrating fish farming with other on-farm activities. The effects of stocking density on production and economic benefits in polyculture and monoculture systems were assessed. It is suggested that the choice of an optimum stocking density is an important aspect in attaining higher performance in any culture system. Investigation on the reproductive biology of Nile tilapia showed that its early breeding behaviour in captivity is not affected by culture system and thus, its production can be improved through proper pond management. The practical application of the results is discussed in detail in each chapter and a synthesis is presented at the end of the thesis.Item Assessment of bioactivity of selected botanicals against the maize weevil, sitophilus zeamals motsch. (Coleopter: curculionidae) in stored sorghum, sorghum bicolor (L.) Moench in northern Nigeria(University of Dar es salaam, 2018) Suleiman, MohammedLaboratory and field studies were conducted with the aim of investigating the efficacy of some botanicals in the management of sitophilus zeamals Motsch infesting stored sorghum. The selected plant species were Euphorbia balsamifera Aiton, Lawsonia inermis L. Mitracarpus hirtus L. and Senna obtusifolia L. Leaf powders, methanolic and ethanolic extracts of the botanicals applied at 2.5, 5.0 and 10.0 x104 ppm were tested for their repellency, toxicity, suppression of development and protectant ability against S. zeamais in the laboratory at 30 ± 2oc and 70 ± 5% R.H. The leaf powders were also applied to four sorghum varieties namely “Farar Kaura” (KF), “Year Gidan Daudu” (YGD) and ICSV 400 at the dose of 5.0% (W/W) and stored in “rhumbus” and store rooms at Dallaje and Pauwa villages, northern Nigeria. In the laboratory, all the botanicals significantly (p<0.05) repelled the weevils with percentage repellency ranging from 40.49 ± 1.44 to 100.00 ± 0.00% in 24 hours after exposure (HAE). The botanicals also resulted in high adult mortality, reduced body protein and inhibited the activity of acetylcholinesterase (AChE) in S. zeamais. Significant percentage oviposition deterrence (POD) ranging from 56.25 ± 2.44 to 94.68 ± 2.68% and complete inhibition rate in adult emergence of the weevils by the botanicals was recorded. The botanicals reduced grain damages, preserved nutrient composition and did not have any adverse effect on germination of the treated sorghum. In storage structures, the insect species found infesting sorghum were Sitophilus zeamais Motsch, Rhyzopertha dominica (F.), Sitotroga cerealella (Olivier), Tribolium casta neum (Herbst), Cryptolestes ferrugineus (Stephens) and Oryzaephilus surinamensis (L.). The plant powders reduced infestation levels of the insect species in different sorghum varieties. The weight losses in the treated varieties varied between 0.50 ± 0.10 and 6.60 ± 0.48% with the highest in FK with S. obtusifolia and the least in ICSV 400 with E. balsamifera. The botanical powders have shown evidence of protecting the sorghum varieties against damages caused by multiple infestations in “rhumbus” and store rooms. It is concluded that all the botanicals tested could serve as eco-friendly alternatives to chemical insecticides in the management of insect pests of sorghum in the storage.Item Assessment of biological characteristics of the whitefly, bemisia tabaci (gennadius) (hemiptera: sternorrhyncha: aleyrodidae) populations transmitting cassava mosaic geminiviruses in Tanzania(University of Dar es Salaam, 2014) Boni, Simon BonifaceCassava, Manihot esculenta (Crantz) is an important staple crop in much of sub-Saharan Africa. Information on the causes of extraordinary fecundity of Bemisia tabaci (Genn.) which is a vector for cassava mosaic geminiviruses (CMGs) that cause cassava mosaic disease (CMD) and its super-abundance in the CMD pandemic areas has been limited. In the present study, genetic sequencing of mtCOI, development duration and mortality of immature stages and response of B. tabaci to cassava varietal influences have been studied on cassava varieties at different CMG infection status in the Lake and Coastal Zones of Tanzania. Four B. tabaci genotypes: TZ CA1, TZ CA2, TZ CA3 and TZ Non-CA were revealed. B. tabaci laid more eggs on CMG-infected cassava plants but with increased survival on CMG-free plants. The development duration of the immature stages of B. tabaci did not significantly differ with CMG infection in both zones but overall, it tended to be shorter in the Coastal Zone than in the Lake Zone. B. tabaci did not show significant preferences for improved CMD-resistant varieties over CMD-susceptible varieties. This study has demonstrated an association of a distinct B. tabaci genotype/biotype, TZ CA1 = UG1, with CMD pandemic and the super-abundance of the vector. The CMD pandemic-based and the CMD non pandemic-based B. tabaci differ in their fitness to the environment, with the former, better favoured than the later. More studies relating this subject are recommended. The knowledge gained from this study can be used in the formulation of effective control and management components of B. tabaci to minimize the spread of the cassava viruses. Ultimately, the findings can contribute to increased productivity of cassava, leading to improved food security and poverty reduction in the country.Item Assessment of local perceptions and potential roles of local institutions in climate change adaptation in Rufiji district, Tanzania(University of Dar es Salaam, 2014) Mwamfupe, Asubisye ObelFarming households in Rufiji district are vulnerable to adverse effects of climate change as they depend on climate-sensitive agriculture for income and food security. Recurrent droughts, changing rainfall patterns, and increasing temperature have been associated with low crop productivity, food shortage and poverty among farming households. Adaptation to perturbations is historical and inevitably local. Local institutions are important in the climate change adaptation as they structure the distribution of climate risks impact, constitute and organize local adaptive responses as well as mediating the same with extra-local institutions. Knowledge on farmers’ adaptive responses and the potential roles of locally based local institutions in the adaptations is crucial in managing and sustaining farming livelihoods amid the changing climate. However, such knowledge is scant. The attempt to fill this gap of knowledge informs the main objective of this study. Specifically, the study aimed at assessing farmers’ perceptions of climate change; assessment of farmers’ vulnerability to climate change impacts; assessing determinants of farmers’ adaptation behaviors; and assessing potential roles of local institutions in facilitating adaptation. Methodological approaches were defined within the mixed-method research design whereby a triangulation of qualitative and quantitative methods was used to collect data from 456 respondents. Quantitative analysis involved using IBM SPSS v. 19 including logit model and qualitative involved content analysis and in some instances NVIVO software. The findings revealed that the majority of farmers perceive long-term changes in temperature and precipitation implying that their areas are increasingly becoming drier and warmer. The study indicates that farming households are vulnerable to climate change impacts such as increased drought frequencies, prevalence of crop disease and pests. These impacts lead to decline in crop production and thus affect household incomes and food security. Farmers; generally respond by adapting at the farm level and household level through the changing of crops, planting dates, livelihood diversification, and storage. The determinants of adaptation have been household characteristics and institutional factors which determine access to information, extension services, and adequate agricultural credits. Despite having several institutions in their communities, most farmers are not integrated in utilization of the potential that local institutions have in order to effectively adapt to climate change. The study concludes that climate change is real in Rufiji as perceived by farmers in respective village. The recommends that in order to improve the role of local institutions in and smallholder farmers’ adaptation to climate change local institutions need to be supported by the government and other stakeholders so that they adequately enable farmers access services and resources necessary for adaptation.Item Assessment of the variations in productivity of bark and phylloclade extracts of Euphorbia Tirucalli L. (African milk bush) as sources of liquid biofuel(University of Dar es Salaam, 2013) Nchimbi, Hamisi, YunusVariations in liquid biofuel quantity and quality of stem bark and phylloclade extracts of Euphorbia tirucalli L. were evaluated based stem diameters of the trees and agro-ecological zones: Dodoma, Dar es Salaam and Mbeya from which the samples had been collected. The effect of planting density on E. tirucalli growth rate and biofuel yield in different agro-ecological zones was also assessed. Soxhlet extraction method with different solvents was used to extract the oil and hydrocarbons. Amount of oil and hydrocarbons was measured by weighing the dried oil and hydrocarbons and results were expressed in grams of the total weight of sample used during the extraction. Oxidative stability (OS) and percent free fatty acid (%FFA) were used to determine the quality of the extracts. Also, the growth rate of E. tirucalli at different densities (i.e. 129,600, 40,000, 14,400 and 6,400 plants per hectare) in different agro-ecological zones and its relation to the quantity of biofuel yield were studied. Data analyses were done using Analysis of Variance and Minitab softwares. Results showed that high amounts of oil (> 16%) and hydrocarbons (> 15%) can be obtained by extraction from stem bark or phylloclade of E. tirucalli. However, significantly higher quantities were obtained from older trees, and at the closest planting densities for samples grown from test plots. Oil and hydrocarbon yields decreased in the order of Dodoma > Mbeya > Dar es Salaam. The study recommends further studies on liquid biofuel from E. tirucalli parts other than wildly grown stem bark and phylloclades in order to optimize their yields and quality at planting densities different from those used in the present study.Item Asset liability management for Tanzania pension funds.(University of Dar es Salaam, 2018) Andongwisye, JohnThis thesis presents a long-term asset liability management for Tanzania pension funds. Two kinds of pension benefits are considered; a commuted (at retirement) and a monthly (old age) pension. A decision factor in the analysis is the increased life expectancy of the members of Tanzania pension funds. As an application, data from NSSF are used. The presentation is divided into two parts. First is a 50 years demographic projection of the fund using a fixed and relatively low return on asset value. Basing on the number of members in 2015, a projection of members and retirees is done. The corresponding amount of contributions, asset values, benefit payouts, and liabilities are also projected. The evaluation of some possible reforms of the fund is done. Then, the growth of asset values using different asset returns is studied. The projection shows that the fund will not be fully sustainable in a long future due to the increase in life expectancy of its members. Second is a risk management based on stochastic programming. The model is based on work by Kouwenberg in $2001$ and includes some features from Tanzania pension system. In contrast with most asset liability management models for pension funds by stochastic programming, liabilities are modeled by a number of years of life expectancy. Scenario trees are generated by using Monte Carlo simulation. Numerical results suggest that, in order to improve a long-term sustainability of the Tanzania pension fund system, it is necessary to make reforms concerning the contribution rate, investment guidelines and formulate target levels (funding ratios) to characterize the pension funds' solvency situation.Item Automatic measuring system for impendance investigation of Mos structures(University of Dar es Salaam, 1985) Mhamilawa, Edward EliahA case is presented to explain the observed frequency dependency of some reported tinuous capacita Cp and conductance G versus bias voltage Vb characteristics of a MOS transistor junction, measured at high frequencies. Based on a discussion on the appropriate electrical model of a device at high frequencies, a series model is chosen for the design of an instrument for measuring parameters of MOS structures. The design principle of the instrument is based on a vector ratio method in which a high frequency signal is transduced by a probe using a special current to voltage transformer and a pair of synchronous detectors, For high accuracy, high frequencies used are down converted to suitable value of 10 kHz using a superheterodyne phase lock loop system and a pair of mixers. The realized instrument is versatile and of low cost. It has the capability of automatic plotting of continuous capacitance Cs with its series resistance Rs versus bias voltage Vb characteristics of semiconductor devices such as MOS capacitors, varactors and similar structures on an X-Y Y recorder. The main features of the instrument include the capability of measuring capacitances from 1 pF to 100 pF and resistances Pram 0 ohm to 1000 ohms in steps of four scale ranges with an accuracy of better than 2 per cent. A bias voltage ranging from -110 V to 1l0 V with a variable sweep range up to ± 10 V and different sweep speeds included together with selectable frequencies of 25, 50 and 100 MHz. Using the developed instrument a set of CS (Vb), Rs(Vb) characteristics of some semiconductor structures are measured and analysed. From the data the frequency dependency of the measured characteristics is observed to be low in agreement with the expected theoretical results. Typically the change of capacitance and its loss resistance of a MOS transistor junction, when frequency is changed from 25 MHz to 100 MHz, have dropped from 48% and 652% to 14% and 40% respectively.Item Banana genetic diversity and diagnostic tools for major nematode species affecting banana in Tanzania(University of Dar es Salaam, 2019) Mmari, Doreen JohnBanana (Musa species EL]) is an important staple food and cash crop for about 30 percent of the total population in Tanzania. Plant parasitic nematodes (PPN), mainly the burrowing and root lesion nematodes are among the major constrains to banana production in Tanzania. The objectives of this study were to establish genetic diversity of banana grown in Tanzania, to identify major PPN affecting banana using morphological and molecular methods and to develop and validate simple and rapid molecular diagnostic tools for PPN. Genetic diversity and population structure of 159 banana varieties from four agro-ecological zones in Tanzania was evaluated using 20 simple sequence repeat (SSR) markers analyzed with the unweight pair group method with arithmetic means (UPGMA) method. The SSR markers revealed high genetic diversity among banana varieties grown in Tanzania and were able to separate banana varieties into two major clusters (cluster A and B) based on their similarities. Of these, 128 distinct genotypes were identified and 31 were overlapping genotypes. Identification of the root lesion and burrowing nematodes using morphological and molecular methods confirmed their presence in most of banana varieties grown in Tanzania. The PPN identified in this study were similar to other banana infesting PPN reported elsewhere in the world especially Europe and Asia. Furthermore, the rapid diagnostic tools designed from the ITS 1 & 2 and LSU D2, D3 expansion segment of rDNA of Pratylenchus spp. and Radopholus similis were able to distinguish these nematodes to species level. Information on genetic diversity and PPN infesting banana is crucial for developing banana varieties resistant to PPN. The simple and rapid molecular diagnostic tools developed in this study can be adopted for routinely screening of PPN infesting banana for sustainable nematode management in Tanzania and beyond.Item Bioactive terpenoids, polyunsaturated fatty acids, and other constituents of two hugonia and some wild mushroom species(University of Dar es Salaam, 2006) Baraza, Lilechi DanstoneUniversity of Dar es Salaam, College of Natural and Applied Science, 2006 This Thesis reports on chemical investigations for fungitoxic, antibacterial, mosquito larvicidal and cytotoxic activity of extracts of Hugonia busseana and H. castaneifolia (Linaceae), Cantharellus mushroom species, and Termitomyces letestui, Agaricus sp. and Lactarius edulis collected in Tanzania. The root bark of H. castaneifolia yielded a new sesquiterpenoid 4a-methoxy-10-himachalen-5|3-ol (hugonianene A), the rosane diterpenoids hugorosenol and 3-deoxy-18-hydroxyhugorosenone and the aldehyde 2- hydroxyhenpentacont-2-enal, 12-hydroxy- 13-methylpodocarpa-9,l 1,13-trien-3-one, caryophyllene oxide, tetracosyl-(£)-ferrulate, hugorosenone, hugonone A and hugonone B. 12-Hydroxy-13-methylpodocarpa-9,ll,13-trien-3-one, hugorosenone and 18-hydroxyhugorosenone, were found to be active principles. H. busseana yielded a new sesquiterpenoid 4a-methoxy-5,9-oxahimachal-9-ene (hugonianene B), 18- hydroxyhugorosane, 3,18-dihydroxyhugoros-l-ene, a mixture of 12-methoxy-13- methylpodocarpa-8,ll,13-triene-3,7-dione and 12-methoxy-13-methylpodocarpa- 1,8,11,13,-tetraene-3,7-dione, hugonone B and 2-hydroxyhenpentacont-2-enal. Fungitoxic bioassay guided analysis of the Cantharellus extracts yielded as the active principles 10-hydroxy-SZT, 12Z-octadecadienoic, (9Z,14Z)-octadecadien-12-ynoic and 9- hydroxy-10is,14Z-dien-12-ynoic acid as well as ergosterol, some of which were detected by HPLC analysis only. Antimicrobial and cytotoxic extracts from L. edulis, Agaricus sp. and T. letestui yielded ergosterol, 5,8-peroxyergosterol and ergosta-5,22- dien-3|3-ol while a mixture of ergosterol and its derivatives was detected by *H NMR and GC/MS analysis of some Agaricus sp. fractions and L. edulis and T. letestui yielded mannitol, a,al,l'-trehalose and ergosta-5,22-dien-3|3-ol. C14, C15, CI6 and C18 fatty acids were also established upon GC-MS analysis of the less polar fractions from T. letestui. Structural determination of all the compounds was based on spectroscopic data.Item Bioethanol and biogas potential of wild cassava, manihot sp: microbial and process conditions for bioconversion(University of Dar es Salaam, 2015) Moshi, Anselm PatrickThis thesis details an evaluation of bioenergy potential of inedible wild cassava for bioethanol and biogas production. Bioconversion processes such as biomass pretreatment; fermentation and anaerobic digestion were optimized, integrated and applied for the production of bioethanol and biogas. Simultaneous saccharification and fermentation (SSF) in stirred tank bioreactor resulted to ethanol titer, productivity and conversion efficiency of 10-11%v/v, 6.5g/L and 98%, respectively. Very high ethanol titer (24% v/v) was achieved from raw starch through SSF-fedbatch mode by the aid of automatic gas potential test system. Metabolic response of a new bacterium Caloramator boliviensis to nutrient dosage and substrate oxidation state revealed the importance of balancing electron flow through co-factor regeneration by formation of ethanol and lactate as electron sinks. At high hydrogen partial pressure (ca.590 pa), ca.76 g/L of glucose was fermented yielding 33 g/L of ethanol. Yields of reducing sugars obtained during liquefaction of cassava starch using enzyme preparation from Bacillus sp. and Aspergillus sp. at 60 °C and 50 °C reached 56% and 66% of theoretical yields, respectively. High energy yield, 15-23 MJ/KgVS added was obtained through co-production of bioethanol and biogas from the wild cassava tuber. Combined ethanol and methane fermentation from wild cassava peels produced 1.2-1.3-fold fuel energy yield compared to only methane and 3-4-fold compared to only bioethanol. This study evaluated the potential of and optimised processes for bioethanol and biogas production from inedible wild cassava.Item Biogeography, diversity and conservation of Tilapia genetic resources in Tanzanian watersheds(University of Dar es Salaam, 2019) Shechonge, Asilatu HamisiTilapia are a group of freshwater fishes that are widely distributed across Africa and are increasingly cultured species as a major source of food. Tanzania is a global hotspot for biodiversity within the genus Oreochromis, with 20 of 32 described species, some considered to be threatened by the IUCN. This work in this thesis reports the current distributions of tilapiine genus Oreochromis in Tanzania, estimates the extent of hybridization between native and non-native species, and quantifies the dietary niches of both native and non-native species within Mindu and Kidatu reservoirs. The work in the thesis also describes the genetic structure of Nile tilapia populations including Lake Tanganyika and other parts of the country, and investigates the relative growth rates of native and non-native species. The approaches used include field surveys, morphometrics, molecular genetics, stomach content analyses, stable isotope analyses and scale growth measures. In total 14 species of Oreochromis species were identified in their native ranges, while three species were found to have established far beyond their native ranges including Nile tilapia (Oreochromis niloticus) and blue-spotted tilapia (Oreochromis leucostictus). The results provided clear evidence of hybridization between native and invasive tilapia in Tanzania. The findings and recommendations are discussed in detail within papers and manuscripts. Measures to conserve the genetic diversity of native species are recommended.Item Bionomics of termite species in coconut farms of Rufiji district, Tanzania(University of Dar es Salaam,, 2012) Materu, Christopher LeonceTermite species richness, evenness and abundance in Rufiji district remain poorly known at a time when biodiversity is being threatened by human activities. Termite distribution, abundance and species richness of Rufiji district were determined between August 2008 and December 2009 in cropland, grassland and forest habitats. The specific objective of the study was to study termite abundance, richness and evenness, as well as to assess the effect of seasonality on termite species richness. Another objective was to identify pest species in coconut nurseries. Termites were sampled along a transect line 200m long and 2m wide replicated twice in each of the three habitat types. Estimates of termite species richness, evenness and abundance were higher in each of three habitats during the wet season. During wet season a total of 14 genera and 2 genus species were sampled. A total of 26,149 individuals were recorded during wet season, 16,820 from cropland, and 4,622 from the forest and 4,707 from the grassland. Termite abundance was significantly higher in the cropland than in both the grassland and the forest habitat (F = 0.0427). Termite species richness was higher in the forest habitat than in other selected habitats but the difference was not significant. Comparison of termite functional groups was significantly different (% 2 = 0.02). Termite pest abundance and seed nut damage were positively correlated although the correlation was not significant (% = 7.815). Losses in coconut seedlings due to termite pests were highest during dry season. Macrotermes sp. was the main cause of the losses. This study provides baseline data on termite communities in Rufiji district. The results can be used for a further research, monitoring and developing sustainable conservation measures in the district.