College of Natural and Applied Sciences

Permanent URI for this community

http://192.168.13.253:4000/handle/123456789/1249

Back to the main page

Browse

Now showing 1 - 20 of 1510

Abundance and diversity of termite species (Isoptera) in the Jozani Chwaka bay national park, Zanzibar
(University of Dar es Salaam, 2014) Mussa, Tumu Ali
The diversity and abundance of termite species (Isoptera) was studied in Jozani Chwaka Bay National Park (JCBNP) from 20 January to 03 February 2013. The scarcity of information for many invertebrates including termites prompted the present study to be conducted. The main objectives of the study were to determine the diversity and abundance of termite species within different habitat types and to determine the microhabitats mostly preferred by termites. The documentation of the data will provide baseline information to the termites found. A total of 5384 individual termites were collected, representing five subfamilies, five genera and five species. The diversity of termite species was highest in the Albizia dominated forest and lowest in the Coral rag and swamp forest. There were significant differences in diversity between different habitat types except in mixed forest and wooded grassland. The abundance of termites was highest in the derived wooded grassland and lowest in Coral rage. In the microhabitats, termites mostly preferred dead and rotten logs as they used them for both nesting and feeding. Differences in environmental conditions and vegetation types are among the important factors which determine the differences in diversity and abundance of termites in JCBNP. Among the genera, Nasutitermes species were found to be dominant probably due to their adaptations to different types of feeding. Psammotermes was the least numerous genus found only in the Albizia dominated forest near the edge of National Park where the habitat had signs of encroachment and is known to be vulnerable to fire, farming and grazing. Education to the local people surrounding the National Park is very important to promote conservation.
The abundance and habitat preference of small mammals in the udzungwa ecosystem, Tanzania.
(University of Dar es Salaam, 1999) Njau, Domician Rogacian
Studies on small mammal abundance and habitat preference were carried out in some habitats within the Udzungwa ecosystem, during the wet and dry seasons of 1997 and 1998. Small mammals were sampled using two types of kill traps (metal snap traps and museum special traps) and two types of live traps (pitfall traps and Sherman traps). In total 12320 trap nights and 1760 bucket nights were realised. This trapping effort yielded 372 individuals of small mammals, 82% of which were 11 species of rodents and the remainder being insectivorous species. Eleven more species were recorded from ad libitum studies. Non-target animals, which included amphibians, birds, reptiles and invertebrates, were accidentally caught during the survey; most of the accidental captures involved pitfall traps. Frogs were caught in all the four trap types used in the study plots. Traps varied in efficiency with which they caught the small mammals. Among non¬pitfall traps the museum specials were the most efficient; this trap type ranked first in the number of animals caught by every 100 trap- nights. Pitfall traps were most efficient (90%) in catching the light small mammals. Traps efficiency also varied through trapping period. Specimens obtained from kill traps were commonly found ruined, where the trap and or scavengers destroyed animal body parts, as such, some important information were usually missed. Some trap locations had higher frequency of small mammal captures than others, mammals caught from such spots within a period of less than twenty four hours were dominated by individuals belonging to the same species. This suggested that intra¬specific association among individuals were most common. Association between individuals of opposite sexes varied on temporal basis, there were more male to female associations during the wet season than during the dry season. This type of individual association was in favour of the breeding (wet) season. The multimanunate rat (Mastomys natalensis) was commonly trapped at 1000 masl in the forest interior. Since the rats are known to occupy habitats associated with human settlements, the results suggest that although no human inhabited areas were currently found in the Udzungwa forests, there had been human settlements in the Udzungwa forests as high as 1000 masl. The abundance of small mammals in the forest was higher where grass cover was founc to dominate the ground cover. On the lowlands, human disturbance of the forest habitat reduced small mammal: diversity. Where such disturbances had encouraged crops, Mastomys natalensis was found to dominate other small mammals; such habitat types supported the highest small mammal biomass. In the montane rain forest the most numerous small mammals were the Crocidura shrews. Multimammate rats (Mastomys natalensis) were the most abundant rodents in the study area (Udzungwa ecosystem); this species was found to dominate small mammals on the lowland (250 masl). The species was most abundant, in cultivated habitats where the highest small mammal live-weight was recorded. Small mammals were more numerous during the wet season when reproduction was also found to be at its peak. Sex ratio seemed not to affect reproduction potential
Accumulation and physiological effects of copper and zinc on the brown macroalga 'Padina Boergesenii' and its use as a bioindicator of heavy metal contamination along the Zanzibar channel
(University of Dar es Salaam, 2001) Mamboya, Florence Alex
The browm macroalga Padina boergesenii Allender & Kraft was used to assess the heavy metal contamination in the Zanzibar Channel. The algal samples were collected from 30 different stations. From Dar es Salaam to Bagamoyo on mainland Tanzania and along the West Coast of Unguja Island, Zanzibar. It was found that the mean concentrations of Mn, Zn, Cu, V, Fe and Al were higher in samples obtained from the mainland stations compared to those obtained from Zanzibar study sites. Of the mentioned metals AI followed by Fe had the highest concentration while Cd had the lowest concentration. Of the five sites with the highest metal contamination, two are found north of Dar es Salaam city, two are near the Kunduchi area and one is found near the centre of Bagamoyo town. Other elements analysed such as Cd, Cr, Ni, and As, fluctuated little and mean concentration of Cd was significantly higher in Zanzibar island side than the mainland side. Laboratory studies were conducted to investigate the ability of P. boergesenii to tolerate and accumulate different copper and zinc concentrations singly and in combination over a period of 21 days. It was found that the accumulation of both copper and zinc increased linearly with increased metal concentration in the growth media. DGR and PE inhibition increased with increase in concentration of the metals in the growth media and exposure time. From laboratory studies it is concluded that the rate of Cu and Zn accumulation in P. boergesenii thalli is directly proportional to their concentrations in growth media. However the presence of high nutrient levels in the growth media lowers metal accumulation. Similarly, Cu and Zn toxicity depends on the amount of dissolved metal in the growth media and exposure time. Generally, it is concluded that the brown algae P. boergesenii can be a useful bioindicator species for examining trends in heavy metal contamination in this region.
Acetylcholinesterase activity and oxidative stress biomarkers in fiddler crabs (Austruca Occidentalis) from mangroves along the Coast of Dar es Salaam, Tanzania
(University of Dar es Salaam, 2019) Kachungwa, James
The aquatic organisms such as crustacean serves as bio indicator to the environmental stressors, which affect the aquatic ecosystems. The main objective of this study was to generate information on the interactive effect of contaminants and salinity on Acetylcholinesterase (AChE) activity and oxidative stress biomarkers in fiddler crabs along the Dar es Salaam coast. The present study investigated the morphological parameters of fiddler erabs, concentration of heavy metals, oxidative stress responses and AChE activity in tissues (hepatopancreas, gills and muscles) of Austruca occidentalis crabs. Heavy metals concentrations in sediments and tissues samples were detected by using Atomic Absorption Spectrophotometer (AAS). The oxidative stress responses by tissues of fiddler crabs were determined by lipid peroxidation (LPO) assay and the AChE activity was determined by endpoint method. The Austruca occidentalis morphological parameters varied greatly among the sites with Kunduchi crabs having much lower morphological parameters. The variation of the parameters is reflected with the level of contamination variation among the study sites. The analysed heavy metals (lead (Pb), zinc (Zn), cadmium (Cd) and chromium (Cr) in Austruca occidentalis tissues concentration was in order of Cr > Zn > Pb > Cd. The concentration of heavy metals varied greatly in relation to the tissues and sites. The LPO levels in tissues of fiddler crabs was relatively high hepatopancreas and were affected by the interactions of factors i.e salinity, sites and tissues. The AChE activity is associated with heavy metals crabs gills are good indicator of heavy metal concentration, in this particular species. Furthermore, the lower AChE activity and relative high LPO level in hepatopancreas for fidder crabs collected from both sites potentiate its ability to be used as biomarker tissue in the particular species. However, futher studies under laboratory set up on biomarkers are needed to validate whether the impacts on MDA and AChE can be used to indicate exposure and effects of heavy metals to fidder crabs.
Acid Mine drainage (AMD) treatment using constructed wetlands
(University of Dar es Salaam, 2005) Mlay, Happiness
A study on the performance of a constructed wetland to treat Acid Mine Drainage (AMD) was carried out in two Horizontal Sub-surface Flow (HSSF) constructed wetlands; one planted with Typha domingensis plants and an unplanted cell used as a control. The wetlands were located at the University of Dar es Salaam (Main Campus). Both units were packed with limestone gravel as substrate and were divided into four equally sized sections along the length: the inlet zone, two central zones and outlet zone. Removal efficiencies of metals and sulphate as well l as change in pH (alkalinity generation) in water were used as performance indicators. It was found that pH increased by about 65 % (from around 4.5-6.0 to about 7.0-8.0), alkali nity generation was almost the same for both cells at about 44.4 % and 44.8 % of the influent akalinity from Typha system and control system, respectively. Sulphate was removed by about 91. I % in the planted wetland and by about 87 % in the control wetland. Copper was removed by 99. l % in the planted wetland and by 72.4 % in the control unit. The retention of copper in planted wetland was about 68% of the initial value and in substrate was about 51 .2 % and 44% of the initial values for Typha un it and control un it, respectively . A dynamic biogeochem ical model was developed by use of the STELLA software version 6.0.1. The model uses different processes to describe the transformation of copper in different compartments and simulates abilities of constructed wetlands to treat Acid Mine Drainage. The results showed that a constructed wetland can be used to treat acid mine drainage.
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 Jeremiah
Recent 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.
Adoption of improved cooking stoves technology and its implications to deforestation: a case of Mpunguzi Ward, Dodoma Municipality
(University of Dar es Salaam, 2013) Chawene, Agnes Boniphace
The problem of deforestation is still a serious issue in Dodoma region. Scarcity of fuel wood caused by deforestation has also been a major problem to the majority of poor people. STT is seriously involved in sensitizing, training and disseminating improved cooking stoves in the rural households in Dodoma Region to combat deforestation. This study used the case study of improved cooking stove project implemented by STT to evaluate the adoption of improved cooking stoves technology and its implications to deforestation in Mpunguzi ward. Both primary and secondary data were used. Primary data were collected through structured questionnaire whereby household interviews, focus group discussion, key informants and direct field observation techniques were employed. The statistical package for social sciences (SPSS) was used to analyze data. A total of 98 individual households were randomly selected and interviewed. The study found that; the adoption of improved cooking stoves was low (38.7 %) compared to the number of households in the ward. However improved cooking stoves had contributed to the reduced fire wood consumption and reduced frequency on firewood collection. Also the improved cooking stove technology have not reduced deforestation as anticipated and as time goes up distance and time on firewood collection is increasing. STT in collaboration with village government need to educate people on the advantages of improved stoves technology as well as ensuring dissemination, project monitoring and enhance the use of improved cooking stoves. Local community involvement in all stages of project formulation and its implementation be insured. Lastly the MNRT should support NGOs and village government so as to conserve forestry resources.
Adoption of indigenous farming practices for adaptation to climate change induced food Insecurity: a case of Busega District in Simiyu Region, Tanzania
(University of Dar es Salaam, 2017) Nyashilu, Issa Musa
This study is about adoption of indigenous farming practices as an adaptation option to climate change induced food insecurity in Busega District, Simiyu Region. The main objective of the study was to assess the potential of promoting crop productivity of smallholder farmers through adoption of indigenous farming practices for adaptation to climate change induced food insecurity. The specific objectives of the study were to: study the rainfall and temperature patterns in the study area from 1986 to 2015, identify the impacts of change in rainfall and temperature on food crop production in the study area from 2006 to 2016 and identify the existing indigenous farming practices in the study area and delineate their potential in adaptation to climate change induced food insecurity. The research adopted random sampling procedure of 10% to select one district out of four, two wards out of fifteen wards. At the household levels the study selected 243 households out of 4,877 of the study villages adhering to 5% sampling protocol. The data were analyzed using Time Series Trend Analysis Software (Mann Kendal Trend Test), Statistical Package for Social Science (SPSS) version 20, Microsoft Excel and XLSTAT computer programme. Results of the analyses indicated that 1.6%, 12.9%, 55.5%, 64.4% and 77.5% of the sample selected for study practice contour bunds, crop rotation, intercropping, zero and minimum tillage, and cover crops respectively, as indigenous farming practices in the villages studied. The study recommends a need to give much priority to the indigenous farming practices in agriculture and food security policies.
Adsorption of heavy metal ions on organosilica composites prepared using rice husks ash as a silica source
(University of Dar es Salaam, 2014) Ligate, Fanuel Josephat
Triaminopropyl-silica hybrids were prepared via post synthetic technique using Rice Husks Ash (RHA) as silica source and (3-trimethoxysilylpropyl) diethylenetriamine. The prepared materials were characterized by acid titration, Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy, Scanning Electron Microscopy-Energy Dispersive X-ray (SEM-EDX) spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), nitrogen adsorption-desorption analysis and thermogravimetric analysis. Results show that the amine group loading of the triaminopropyl-silica hybrid prepared using rice husks ash (TSH-R) was 2.15 mmol/g. The TSH-R was found to have characteristic functional groups, namely, O-Si-O (900-1150 cm-1), CH (2800-3000 cm-1), O-H (3000-3500 cm-1) and N-H (1530 cm-1) which were obtained by ATR-FTIR analysis. SEM and FE-SEM micrographs of the prepared materials showed rough surfaces with protuberances, cracks and holes. The RHA, rice husks silica (RHS) and TSH-R materials had average particle sizes of 336.8, 296.4 and 1054.1 nm, respectively. EDX gave the elemental composition whereby Si and O were present in high proportion in all samples. The BET surface areas of RHA, RHS and TSH-R were 17.8, 20.2 and 5.7 m2/g respectively. The total pore volumes were 0.43 cm3/g for RHA, 0.49 cm-3/g for RHS and 0.02 cm3/g for TSH-R. On the other hand, the average pore width of RHA, RHS and TSH-R were 95.9, 97.6 and 17.3 nm respectively. The materials had pores in the mesoporous range and exhibited very small change in weight beyond 500 ºC. Adsorption studies of Ni(II), Zn(II), Pb(II), Cu(II) and Co(II) ions showed that RHA and TSH-R were good adsorbents with the average maximum adsorption of 99 and 95% for RHA and TSH-R, respectively when 1.0 g of adsorbent and initial metal ions concentration of 21 - 27 mg/L at pH 4 were employed. Both Langmuir and Freundlich isotherms indicated that the adsorption was favorable. Thus RHA and TSH-R can be used to remove mixtures of toxic heavy metals from contaminated water. Based on the findings of this study RHA is the best adsorbent because, it has overall superior adsorptive properties and it is cost effective.
Advancing rainwater harvesting as a strategy to improve water access in Kinondoni District
(University of Dar es Salaam, 2013) Dismas, Joshua
Inadequate water supply from DAWASCO affects communities in different wards of Kinondoni District. Currently total demand of water in Dar es Salaam is 450,000m per day while its production capacity is only 350,000m per day. Methods that were used in data collection were interview, questionnaire, observation, and laboratory tests. SPSS tool was used for data analysis. The study aimed to assess opportunities for application of RWH technologies, challenges for installation and maintenance of RWH technologies and final to propose creation of financial and technical institutions for implementation of RWH technologies. Rooftop RWH systems with proper components and desirable maintenance were found to bear good quality of water for domestic use than other systems. On laboratory tests rainwater revealed to be better than most sources of water available in the study area although its Ph in plastic storages were observed to be less than required standard for domestic use i.e Ph below minimum limit of 6.5. Lack of knowledge was identified as the main factor that hinders adoption of RWH technology as the people have the idea that rainwater cannot be preserved over a long period of time without being spoilt and invaded by worms. Also initial investment cost was among the reasons deterring adoption of RWH especially to households with low income. Therefore for improving adoption rate of RWH there should be an integrated participation of different stakeholders such as Government, education institutions, financial institutions, construction companies and NGOs to educate and support communities on RWH technologies’ challenges.
Aflatoxin levels in sunflower seeds, feeds, seed cakes, oil and cow milk collected from Singida
(University of Dar es Salaam, 2016) Salum, Mohamed
Aflatoxin contamination in various food, animal products and animal feed pose health concerns to human that rely on consumption of these products. The study analysed the levels of aflatoxin contamination in sunflower seeds, seed products and raw cow milk collected from Singida. The samples of sunflower seeds (40), seed cake (16), sunflower based seed cake feeds (20), oil (20) and raw milk from cow feed on sunflower based seed cake feeds (37) were analysed for aflatoxin using HPLC. of the analysed raw cow milk samples 83.78% were contaminated with AFMi ranging between 0.065 to 2.007 ng L''of which (86.5%) exceeded the EC and TFDA tolerable limits of 0.05 ng mL’1. About 13 (65%) samples of sunflower based animal feed were contaminated with AFBi ranging between 2.184 to 20.465 ng g"1, of which 61.53% exceeded the EC, TBS and TFDA tolerable limits of 5 ng g’ for animal feed. Nine (53%) samples of sunflower seed cakes were contaminated with AFBi ranging between 1.004 to 11.030 ng g'1, with 3 (25%) samples exceeding the EC limits of 5 ng g'1. Four (10%) of sunflower seed samples were contaminated with AFBi ranging between 0.428 to 218.139 ng g'1, with 3(75%) samples exceeding the EC limits of 2 ng g'1 for oil nuts. Seventeen (80.9%) raw sunflower oil samples were contaminated with aflatoxins ranging between 0.255 to 2.555 ng ml/'with 3 (17.65%) samples exceeding the EC, limits of 2 ng mL'1 for edible oil. Therefore, it is evident that the raw milk and unrefined sunflower oil from Singida are posing safety concern for human consumptions. Therefore, it is important to conduct time to time aflatoxin surveillance on these kinds of food to ensure human health safety.
African traditional brews: quality, chemical constitution and health aspects.
(University of Dar es Salaam, 2000) Saria, Josephat Alexender
Wide quality variability, unpredictability and lack of routine scientific quality control in African alcoholic beverages leads to uncertainty in the identity and quality of what is being consumed. The problem is important as these products are mass consumed and command the largest market share in the alcohol market. Ethanol, the target of fermantative conversion of sugar, is variable both within and between brands and ranges from ca. 3.5 to 8.2 % v/v in brews examined in this work. Fluctuating levels of unwanted fermentation by-products have been detected: methanol (0.3 - 3.2 ppm), butanol (9.8 - 39.6 ppm), propanol (10.6 - 51.4 ppm), isoamyl alcohol (42.5 - 231.6 ppm), furfural (56.8 - 412.3 ppm) and acetaldehyde (10.7 - 44.9 ppm). Metallic contaminants in some traditional brews have been found to exceed the WHO and Tanzanian Standards (TZS) for drinking water. In about 25 % of the processing water samples analysed, cadmium levels exceeded the WHO and TZS limits. Zinc levels in processing water were lower than the specified limits. Nutrient levels like fats range between 0:028 - 0.585 %,w/w while the levels of carbohydrates range between 3.395- 11.036 %,w/w. On average, protein content is high in maize/cereal based types but lowest in plant sap derived brands. Traditional brews generally have higher calorific value than Tanzania Breweries Ltd (TBL) brands. However, when the ethanol calorific value is included, the values double. This means consumers derive ca. 50% of their calorific needs from this objectionable source. Bacterial contamination for coconut palm wine brand averages of 11.20 ± 4.15/100 ml faecal coliform (F.C.) and 113.20 ± 11.4 /100 ml total coliform (T.C.). Some processing water samples have recorded high coliform (T.C.) 3,629.50 ± 440/100 ml (F.C.) 241.00 ± 22.5/ 100 ml). Contamination is not traceable to the plant sap but to handling. The quality of brew is dependent on shelf life and temperature. The quality however, continues to deteriorates and attains a critical shelf life at 17 hours (30°C), while at 40°C, this status was attained after 12 hours. At 17°C this is lengthened to ca. 32 hours. The levels of furfural increase with extent of fermentation. Rise in temperature favours the formation of furfural via the Amador Rearrangement Product (ARP) via 1,2,-enolisation. The concentration of protein decreases with shelf life where the rate is high in the first 10 hours, probably this interval is dominated by formation of Free a- Amino Acid (FAN).
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.
Agricultural adaptation strategies to climate change and its implication to household livelihood in lowland coastal areas: a case study of Kitonga village, Bagamoyo district
(University of Dar es Salaam, 2014) Mkama, Wilbard
This study examined agricultural adaptation strategies to the impact of climate change in Kitonga coastal village. Household interviews, key informants, focus group discussions and participatory field observation complemented each other in addressing the study objectives. Qualitative information was analyzed using content analysis while the quantitative information was processed by using SPSS program. Finding from the study has shown that the community understands climate change in terms of climatic variables such as rainfall and temperature. Climate change evidences identified include late rainfalls, decreasing crop productivity, increasing temperature, increased incidences of drought, and recurrent food shortages. Furthermore the community acknowledged major existing adaption strategies as timing of farm operations, growing water loving crops and crops rotation. Dominant livelihood assets influencing adoption of different agricultural strategies identified included financial assets such as microfinance schemes, physical assets such as fertile land , and social assets including strong social group that enhance social cohesion. Institutions have assisted vulnerable groups to adapt to impacts of climate change, climate change information dissemination and loans to support adaptation. To increase effectiveness of agricultural adaptation strategies, the study recommends technical assistance to village agriculture extension officers and increase financial support to improve their livelihood.
Air pollutants from vegetation, forestry and wetlands (land use) sector in Tanzania
(University of Dar es Salaam, 2009) Kisungwe, Benjamin
The purpose of this study was to determine the magnitude of national air pollution emissions from vegetation fires, forestry and wetlands in Tanzania that are directly attributable to human activity from 1995 to 2005.IPCC method was used for the estimation of green- house gases CO2, CO, CH4, NOx and N2O. SEI procedure for estimating annual emissions from the burning of forests and grasslands was used for non green-house gases (SO2, NMVOC, PM10, PM2.S and NH3). Information on forest fires, area of flooded land and annual forest converted area was obtained from the Ministry of Natural Resources and Forestry, Tanzania Bureau of Statistics, FAO Website, IPCC guideline, CEEST, and TANESCO. Emission factors from IPCC guidelines and SEI were used as default values. The results obtained in this study showed that forest fires, forest conversion and flooded land were the major sub-sectors of greenhouse and non-greenhouse gases emissions. CO2 was the major pollutant emitted of all greenhouse gases from forest and grassland conversion subsector. The emissions from wetland revealed that Mtera dam emitted more methane than other hydro dams during the study period. These variations were due to differences in surface area of the water body. The land-use change and forestry and wetland subsectors were significant emitters, while vegetation fires subsector was not significant. In order to exploit the results of this study Tanzania should develop country emission factors, proper data bank for land use and forest fire and re-evaluate the GHG and non- GHG emissions.
Algorithms for the assembly line balancing problem: a case study of the Matsushita Electric Company in Tanzania
(University of Dar es Salaam, 2000) Ndunguru, Asteria Canisius
In this research, a Tabu search algorithm for the Assembly Line Balancing problem type-1 and type-2 are described. The Assembly Line Balancing Problem type-1 (ALBP1), is the problem of minimising the number of workstations for a given cycle time, whereas type-2 (ALBP-2) is to maximise production rate, or equivalently to minimise the sum of idle times for a given number of workstations. In both problem types, precedence constraints between the tasks have to be considered. Tabu Search and Kilbride & Wester algorithms for the assembly line balancing problem type-1 are developed and comparison of performances of the two heuristics over the assembly line balancing is done. Lastly, the exact approach is applied to a small sized assembly line balancing problem type-1. Its results are compared with the results of Tabu Search and Kilbride & Wester heuristics over the assembly line balancing problem type-1 to prove their efficiency. It is concluded that, .both Tabu search and Kilbride & Wester algorithms are good approaches to the Assembly Line Balancing Problem type-1
Allocation of buses to networks with overlapping routes: a case study of city of Dar es Salaam.
(University of Dar es Salaam, 2013) Ngulo, Uledi Ayubu
This project addresses the optimization model for bus scheduling problem. In general, the problem of allocation can be defined in the following terms: Given the origin destination transit matrix for the bus trips for the design period and the underlying bus network characterised by the overlapping routes, how optimally to allocate the buses among these routes? The problem formulation is developed which recognizes passenger route choice behaviour, and seeks to minimize a func¬tion of passenger waiting time and crowding level of the passengers in the bus subject to constraints on the available number of buses and enough capacity to be provided on each route so as to carry all passengers who would select it. The bus scheduling problem is solved in two stages: In the first stage, the frequencies required to handle the maximum loaded link on each route are identified. In the second stage, the surplus allocation is illustrated for the simple objective of minimizing the maximum crowding level on any route. Tabu search algorithm has been used to solve the problem of scheduling of surplus fleet. The model has been applied to Dar es salaam city network and found that about 93.6% of the average waiting time obtained by SUMATRA have been minimized. This directly minimized the overcrowding of passengers at the bus stop, as a result the maximum crowding level of the passengers in the buses have been minimized.
The altitudinal and seasonal use of riverine forests by birds in the uluguru mountains, Tanzania
(Unversity of Dar es Salaam, 2007) Werema, Chacha
Seasonal and altitudinal distribution of birds was studied between May - 2005 to July 2006 at five altitudes (300, 600, 900, 1200 and 1500 m above sea level) along a riverine forest in Uluguru Mountains, Tanzania. The study aimed at examining the influence of seasons on bird abundant and diversity, and on the relative abundance of birds in different feeding guilds in the riverine vegetation, along the elevation gradient. Furthemiore, the study examined whether forest dependent species were using the riverine forest in both seasons.With the use of mist netting and ringing (a total of 73,440 metre-net hrs), 150 one- hour Timed Species Counts and general field observations, 128 species in 42 families and 11 Orders were identified in this study- of these 58.9% were forest dependent species which at each altitude sampled, were more numerous than non- forest species. Species richnns decreased with increasing elevation. Some bird species, particularly forest dependent ones, moved down to lower altitudes along the riverine forestt during the cold season and during the hot season they migrated to higher altitude forest. The seasonal and altitudinal movements were revealed by ringing recaptures at different altitudes. Due to the presence of seasonal migrants and threatened species during the cold season at low elevations, and the intra-African migrants in the Ulugurus, the study recommends the need for a strict protection and maintenance of the forest along the entire altitudinal gradient, not only in the Ulugurus but also elsewhere. It further stresses the importance of designing wildlife corridors between forest reserves to permit seasonal vertical altitudinal movements of wildlife as well as dispersal into areas of similar altitude.
Altitudinal migration of birds in the Uluguru mountains, Tanzania: effects of forest fragmentation, altitude, fire, arthropod food and habitat structure
(University of Dar es Salaam, 2015) Werema, Chacha
A study was conducted to assess the effects of forest fragmentation, altitude, seasons, fire, vegetation structure and distance from the source habitat on altitudinal migration of birds at the lower altitude forest fragments and forest edges between 180 – 1300 m above sea level in the Uluguru Mountains, Tanzania. This was conducted using mist netting augmented by audio-visual observations during the cold and hot seasons between 2010 and 2013. Twenty one species, all of them forest dependent had higher abundances during the cold season than in the hot season at most of the study sites. There was no significant relationship between area of the forest fragement and the number of species of altitudinal migrants. The abundances and species diversities of altitudinal migrants were higher during the cold season than in the hot season. Forest fragments located at relatively higher altitudes close to the source habitat, the Uluguru Nature Reserve, had more species, higher abundances and diversities of altitudinal migrants than in the relatively lower altitude forest fragments. Density of trees was positively correlated with the number of species and diversity of altitudinal migrants. Fire negatively affected the abundance of the migrants suggesting that burning of forests can lead to loss of some bird species and restricted use of lower altitude forests by some altitudinal migrants. Due to the isolation of the forest fragments studied and possible inhibition of movements of some of the altitudinal migrants at forest edges, the results of this study have implications for conservation; corridors linking higher with lower altitude forests are needed and further threats to the forest such as fragmentation, creation of forest edges and fires should be reduced
Anaerobic co-digestion of fresh water hyacinth and fish waste in batch cultures.
(University of Dar es Salaam, 2002) Machunda, Revocatus
Methane production potential of individual and mixed fractions of fresh water hyacinth and fish waste was studied in batch cultures. The study also established viable counts of selected pathogens and investigated the effects of anaerobic digestion on their reduction. The fish waste contained 32%TS, 91%VS, and a C:N ratio of 6:1. The fresh water hyacinth contained 7%TS, 79%VS (dry weight), and a C:N ratio of 23:1. The substrate concentration of S.8 to 46.6 gVS per litre of fermenter volume for the fish waste was degraded by 30 to 4S% and gave methane yields in the range of 19 to 3S ml per gram of VS digested. The substrate concentration of 1.16 to 16.6 gVS per litre of fermenter volume for fresh water hyacinth was degraded by 21 to 72% and gave methane yields in the range of 29 to S6 ml per gram of VS digested. Codigestion of fish waste and fresh water hyacinth at a ratio of 1:4 parts gave the highest methane yield of about 20 ml per gram of volatile solids digested and were degraded by 2S%. This yield is lower by 42 and 64% than that obtained for the anaerobic digestion of individual fractions of fish waste and fresh water hyacinth, respectively. The effect of anaerobic digestion on the reduction of total coliforms, fecal coliforms, Clostridium perfringes and Salmonella species was investigated at mesophilic temperature of 30 °C, in the mixture of fish waste and fresh water hyacinth for 21days. Anaerobic stabilization of the mixture of fish waste and water hyacinth resulted into total destruction of fecal coliforms, and Salmonella species. The total coliforms was reduced by 87 °lo and Clostridium perfringes was reduced by 67%. This study demonstrates that there is a need for optimizing the anaerobic digestion of the combined fractions to improve their yields, and that the mesophilic temperature of 30 °C is effective in reducing the counts of pathogens in the mixed fractions of these substrates.

Browse

Browsing College of Natural and Applied Sciences by Title

Results Per Page

Sort Options