Tanzania Journal of Science

Application of combined geophysical and archaeological survey techniques: a case study of Singida Region, Tanzania

Makarius Peter Itambu — 2024-10-02

The seismically active Singida region in central Tanzania lies at the edge of the East African Rift System (EARS) which is locally designated the Gregory Rift. The archaeological record of the region, especially in the eastern part of the Ikungi District, unlike that of northern Tanzania, is comparatively unknown, despite early archaeological expeditions hinting at its potential. Recent research in the eastern area suggests that it preserves a long record of hominin occupation spanning the Early to Late Stone Age. This interdisciplinary field work, carried out between August 2022 to August 2023, resulted in the discovery of a relatively deep package of Quaternary deposits, revealing assemblages of artifacts dating from Early Stone Age (ESA) to Middle Stone Age (MSA) periods. This testifies, for the first time, to a long term and more scattered human occupation in this part of this central region close to the famed Oldupai Gorge, since other sites were found across the Gregory scarp and the nearby Singida-Arusha highway. We also utilized magnetic surveys acquired with a Cesium vapor magnetometer coupled with magnetic susceptibility measurements using a SM-30 device in the sites, which revealed ancient fireplaces potteries, furnaces, Iron ore and other metallic materials of various ages, hence proving the success of multiple applications of rock magnetism combined with archaeological approaches in the region. We provide evidence of pedological and archaeological records of the end of the African Humid Period (AHP) in this eastern part of the region and possibly other later abrupt arid events which exhibit synchronicity with similar events recorded in sediment archives from Lake Victoria or further South (i.e., Lake Nyasa). This promising venue of investigation bears much potential and calls for further study. Finally, we question the potential drivers that could possibly explain human settlements or migration pathways in conjunction with the shift from hunting-gathering to pastoralism.

Keywords: Magnetic mapping; Low-field magnetic susceptibility; Archaeological sites; Heritage resources; Natural resources

The Impact of Land Use and Land Cover Change on Water Quality in Lake Victoria Catchment: A Case Study of Nkangabile River at Nyegezi Bay, Tanzania

Charles A Mashafi — 2024-10-02

Understanding the trends and impacts of anthropogenic activities in the water basins and catchments is key to the effective management and conservation of aquatic environments. This study analyses the land use and land cover (LULC) changes in the Nkangabile catchment and their impacts on water quality in the Nyegezi Bay of Lake Victoria, Tanzanian side. GIS and Remote sensing techniques were used to analyze the multi-temporal changes in LULC that occurred in the past 30 years from 1983 to 2013, split into four epochs of 10-year intervals. The changes in LULC were analyzed using image differencing and cross-tabulation for pairwise methods. The results indicated an increasing deterioration of water quality and a considerable transformation of LULC between the four epochs and more so in the long-term period from 1983 to 2013. The study provides evidence that LULC changes are accelerated by anthropogenic activities that severely affect the ecosystem through increased water pollution. Balancing human activities through proper land use planning as well as conservation awareness are strongly recommended to ensure adequate protection of the Lake Victoria ecosystem.

Keywords: Land use and Land cover change, Nkangabile catchment, Landsat, Support Vector Machine, Water quality

Adsorptive Performance of Composite of Sugarcane Bagasse Fibres and Multiwalled Carbon Nanotubes for Simultaneous Removal of Multi–pollutants from Wastewaters

Joseph W Sengasu — 2024-10-02

This paper reports on the performance of the prepared Sugarcane Bagasse Fibres – Multiwalled Carbon Nanotubes (SBF–MWCNTs) composite for simultaneous removal of Crystal Violet (CV), Pb(II), Cr(III), Cd(II) and Co(II) from the effluent using a fixed bed method. Different composites of SBF–MWCNTs biosorbent were prepared from mixtures of varied ratios of SBF and MWCNTs at 25 °C. The SBF–MWCNTs materials were characterized by FT-IR spectroscopy and thermogravimetric analysis. Crystallinity index and swelling behaviour of the materials were also determined. Thomas model linear equation was applied in the assessment of pollutants adsorption performance at different conditions. With a column height of 8 cm containing 1.5 g of SBF–MWCNTs, flow rate of 2.5 mL min^-1, pH > 6, and pollutant initial concentrations of ≤25 mg/L, the SBF–MWCNTs composite containing 2% MWCNTs had higher pollutants adsorption capacity (mg/L), 6.61 ± 0.092 Pb(II), 4.78 ± 0.132 CV, 4.58 ± 0.080 Cr(III), 4.09 ± 0.181 Cd(II), 2.98 ± 0.230 Co(II). Whereas, that of unmodified fibres (SBF) were 5.53 ± 0.056 Pb(II), 4.48 ± 0.091 CV, 3.77 ± 0.072 Cr(III), 3.41 ± 0.050 Cd(II) and 2.42 ± 0.031 Co(II). Statistical analysis at 0.05 significance level has shown that adsorption capacity of each contaminant by the SBF–MWCNTs is significantly higher than that of SBF. These results indicate that SBF–MWCNTs composite is a potential biosorbent for the removal of multi–pollutants from aqueous systems.

Keywords: Wastewater treatment; Multi–pollutants; Carbon nanotubes; Sugarcane bagasse; Fixed bed

Concentrations of Rare Earth and Valuable Elements in Mkuju Uranium Cores for Recovery

Joshua Ndalusanye — 2024-10-02

Rare earth elements and valuable elements within Mkuju uranium core samples were analysed using EDXRF. Mean elemental concentrations for selected elements including Al, P, K, Ti, V, Mn, Fe, Y, Mo, Ag, Ba, La, Ce, and U were determined as 96445.79 μg/g, 547.19 μg/g, 25296.88 μg/g, 5926.33 μg/g, 116.26 μg/g, 455.02 μg/g, 60.1 μg/g, 142.34 μg/g, 15.8 μg/g, 493.98 μg/g, 67.53 μg/g, 118.68 μg/g, and 128.37 μg/g respectively. The Rare Earth elements: Y, La and Ce and valuable elements: Mo, Ag and U have enrichment factor of EF >1.5 which indicates that, these elements were formed from rocks through geological processes and can be mined at a profit. The valuable elements AL, P, K, Ti, V, Mn, Fe and Ba have enrichment factor of EF ≤ 1.5 which indicates that, these elements were formed from natural weathering processes. It is concluded that, despite the low concentration of the Rare Earth and valuable elements, the possibility of recovering both valuable and Rare Earth elements in Mkuju deposit is significant.

Keywords: Rare Earth; Valuable Elements; Mkuju; EDXRF

Performance of a Bipolar Output Voltage DC-DC Converter for Voltage Regulation for Solar PV System Application

Stampinus M. Stephano — 2024-10-02

A combined Single-Ended Primary-Inductor Converter (SEPIC) and Cuk DC-DC converter that provides a bipolar outputs voltage at the DC bus is widely used in applications especially solar photovoltaic (SPV) system. Maintaining constant output voltages at the DC bus under variable loads and input voltage from SPV is of great interest to many researchers. This paper presents a 400 W mathematical model of a combined SEPIC and Cuk DC-DC converter through state space averaging (SSA) in a continuous conduction mode (CCM). A nested voltage and current control loops are used to regulate voltage and increase the performance of the converter. These controls use Proportional-Integral (PI) controllers to track the desired input reference signal and eliminate any disturbance from the load. The entire model with its control algorithm was modelled in MATLAB/Simulink environment and validation results to evaluate its performance are presented. The controller was able to maintain required bus voltage of 24 V DC and -/+12 V at the output DC bus. DC bus voltage regulation was tested at varying input voltages and varying loads connected at the output, where, in all those scenarios, the converter could regulate its output voltage to required value.

Radiation Doses to Patients Undergoing Common X-ray Examinations from Selected hospitals in Dar es Salaam and Zanzibar, Tanzania

Ali O. Masoud — 2024-10-02

This study involved 300 patients, comprising 113 females and 187 males, from six X-ray units. The study focused on evaluating the patient dose for common X-ray examinations at selected hospitals in Dar es Salaam and Zanzibar, Tanzania. The achieved results were compared with previous studies and Diagnostic Reference Levels (DRLs). Entrance surface air kerma (ESAK) was calculated for chest posteroanterior (PA), cervical spine anteroposterior/lateral (AP/Lat), abdomen anteroposterior (AP), and lumbar spine anteroposterior/lateral (AP/LAT) examinations. The study results revealed the following average ESAK values: chest posteroanterior (PA), 0.34 mGy; abdomen anteroposterior (AP), 1.92 mGy; lumbar spine anteroposterior (AP), 2.78 mGy; and lumbar spine lateral (Lat), 11.8 mGy. When these results were compared to previous published results, there was only a slight deviation among calculated ESAK. A serious deviation was found in chest examinations. The results from this study highlight the importance of optimizing and justifying procedures, as well as the establishment of National Diagnostic Reference Levels (DRLs). The values described in this study could further contribute to the development of local, regional, and international DRLs

Keywords: Entrance Surface Dose; Diagnostic Reference level; Diagnostic radiology

Exergy analysis and performance testing of a gravitational water vortex turbine runner for small hydropower plants: An Experimental Approach

Adam Faraji — 2024-10-02

their low initial investment, simple design, ease of maintenance, and low head utilization. However, the technology suffers from poor performance issues caused by the non-optimized parameters of its crucial components, such as the runner. In this study, the performance of a runner (16° blade-hub angle, six blades, and a curved blade profile) for a GWVPP was experimentally examined. The study also employed an exergy analysis. The experimental results revealed that the efficiency of the GWVPP system was in the range of 9.84% to 25.35%, the torque was in the range of 0.08 to 0.23 Nm, and the output power was in the range of 2.96 to 7.33 W. Furthermore, an exergy analysis of the system showed an exergy efficiency of 43.58%. Additionally, the error analysis of the GWVPP revealed ranges of 0.1 - 0.5 W for power, 0.01 - 0.03 Nm for torque, and 1.3–3.1% for efficiency, suggesting that the experimental setup and instrumentation of this study were reasonably accurate. Based on the results, the new vortex runner and GWVPP system are recommended for energy generation in low-head, low-flow small hydropower plants.

Keywords – Micro-hydropower; gravitational water vortex; runner; exergy efficiency; test rig

Assessment of the Dose Coverage at the PTV for EBRT for Cervical Cancer Treatment Plan Using AAA Varian Eclipse TPS at Ocean Road Cancer Institute, Tanzania

Kelvin G. Ngowi — 2024-10-02

The implementation of the Eclipse treatment planning system software (Version 15.1) at Ocean Road Cancer Institute (ORCI), Tanzania has made the Anisotropic Analytical Algorithm (AAA) the necessary routine tool for dose calculations. However, the accuracy of the AAA algorithm in planning doses specifically for cervical cancer treatment is not well known. Therefore, this study investigated the accuracy of the AAA in dose calculation in terms of the dose coverage at the Plan Target Volume (PTV) for cervical cancer treatment at the ORCI. 50 treatment plans of adult patients with International Federation of Gynecology and Obstetrics (FIGO) stage IB-IIIB cervical cancer who underwent 3D-CRT were analyzed. The results show that most of the patients received at least 95% of the prescribed dose, averaging 48.3 Gy, which is about 96.6% of the prescription. The average maximum dose was about 53.7 Gy, equivalent to 107.4% of the prescribed dose. When compared to other studies, minor dosimetric differences, typically less than 2% for all the PTV dose parameters, were observed. In conclusion, the results affirm that the Eclipse AAA algorithm is sufficiently accurate for dose calculations for cervical cancer treatment planning at the ORCI.

Keywords: AAA; Cervical cancer; FIGO; PTV; TPS

The Occurrence and Variations of Total Aflatoxins and Aflatoxin B1 in Different Types of Chicken Feeds Marketed in Dar es Salaam, Tanzania

Mambaga S. Muja — 2024-10-02

This paper reports on the occurrence and variation of total aflatoxins (TAF) and aflatoxin B₁ (AFB₁) in different types of chicken feeds collected from various locations in Dar es Salaam. A total of 63 chicken feed samples based on cotton seed hulls, sunflower seed hulls, maize bran and mixed feeds were analysed using HPLC-FLD. It was revealed that all samples were contaminated with both TAF and AFB₁, varying significantly with respect to their types. Specifically, 52.9% of the cotton seed hulls and 64.7% of maize bran samples exceeded the set tolerable limit of 5 ng g⁻¹ for AFB₁. All sunflower seed hull samples were contaminated, showing varying mean concentrations of TAF across the sites: Manzese (150.48 ng g⁻¹), Mbagala (56.20 ng g⁻¹), Bunju (49.08 ng g⁻¹) and Kigamboni (33.83 ng g⁻¹). Remarkably, all chicken feed samples from the poultry farms were contaminated with levels beyond the recommended international maximum tolerable limit of 20 ng g⁻¹ of TAF for feeds with levels decreasing from Farm C (77.71 ng g⁻¹), Farm A (48.19 ng g⁻¹), Farm E (38.95 ng g⁻¹) and Farm F (24.48 ng g⁻¹). These findings call for urgent stringent quality control measures to mitigate aflatoxin contamination in chicken feeds, thereby safeguarding animal health and preventing potential health risks to humans.

Keywords: Aflatoxins; High Performance Liquid Chromatography; Poultry feeds; Contamination; Mycotoxins

Effects of Operating Parameters on the Higher Heating Value of Kitchen Waste during Hydrothermal Carbonization

Veronika Gerald Kimario — 2024-10-02

Hydrothermal carbonization (HTC) is a promising waste to energy technology for conversion of organic wastes with high water contents. There have been relatively few studies focused on evaluating the HTC of solid waste (SW). The studies have provided valuable information regarding HTC feasibility and potential environmental benefits. However, they lack the data necessary to understand how carbonization product composition and reaction extent change with the variation of operating parameter. This study sought to characterize kitchen waste from a university restaurant, to assess the impact of operating parameters on hydro-char and evaluate its potential as a solid fuel. The methodology for characterization was based on proximate analysis, ultimate analysis and calorific value. A ratio of dry sample to water of 1:9 was used to make a wet sample and stirred at 180 rpm in a thermal reactor under controlled HTC conditions. The results from proximate analysis revealed that moisture content, volatile matter, ash content and fixed carbon content were 9.6%, 65.1%, 13.6%, and 11.9% respectively. The ultimate analysis showed that carbon, hydrogen, nitrogen, Sulphur and oxygen were 48.8, 0.5, 0.4, 0.5 and 45.3% respectively. Mass yield of hydro-char decreased for all samples with increasing HTC reaction temperature. ANOVA confirmed the adequacy of the model, yielding R2 and adjusted R2 values of 0.8630 and 0.7398, respectively with a P value of 0.003 and F-value of 7.00. The high heating value, ultimate analysis and proximate analysis suggested that the hydro char from kitchen waste can potentially be utilized as a solid fuel.

Isolation and Characterization of Yeast from Sisal Boles for Bioethanol Production

Neema Msuya — 2024-10-02

diversity of microorganism species, including yeast that can be utilized for bioethanol production. The objective of the study was to isolate yeast cells from sisal boles juice for bioethanol production. Sisal boles for juice extraction were randomly collected from Ubena sisal estate, Pwani region. To preserve the targeted microorganisms cold juice pressing method was used. Pour plate method was used on Potato Dextrose Agar and four distinct colonies were formed and repeatedly sub-cultured to obtain four pure yeast isolates. The juice yield was only 510 mL per kg of sisal bole, which is below the yield for autoclaved sisal bole obtained by other researchers. The yeast identified was concluded to be Saccharomyces cerevisiae based on the macroscopic and microscopic morphological observations. Isolated S. cerevisiae is better conditioned for fermentation of sisal bole juice to various products, including bioethanol. Upon the fermentation and temperature tolerance test, all the indigenous yeast isolates could ferment glucose, sucrose, maltose and fructose and tolerate incubation temperatures up to 45ºC. Therefore, the indigenous S. cerevisiae isolates can reliably be conditioned for use in ethanol production using sisal wastes.

Effect of Alkali Treatment on the Chemical Composition and Dyeability of Sisal Fibers

Cosmas F Kindole — 2024-10-02

Recently, natural fibers have gained significant attention from many researchers due to the global demand for natural products with low environmental impacts. Sisal (Agave Sisalana), is among the important natural fibers with substantial potential to flourish due to their outstanding properties, including high strength, good absorbency, and abundant availability. However, utilization of these fibers is yet to be fully explored, probably due to their stiff and coarse nature, which limits the overall applications of this sustainable fiber. This study, therefore, investigated the effect of alkali treatment on the chemical composition and dyeability of sisal fibers as a way of adding value to the fiber and potentially broadening their applications. The findings of this study have shown that alkali treatment decreased significantly the amount of hemicellulose and lignin from 10.6% and 10.7% to 4.9% and 6.4%, respectively. However, the cellulose content slightly increased from 64.6% to 64.7%. The decrease in amounts of hemicellulose and lignin was thought to be due to their high sensitivity to the action of alkali. Furthermore, the chemical treatment improved the dyeability of sisal fibers when both reactive and vat dyes were used, resulting in fibers with higher levels of dye exhaustion and improved wash fastness properties. Overall, the results suggest that alkali treatment not only modified the surface structure of sisal fibers but also improved their dyeability with both reactive and vat dyes. This will contribute to expanding the practical applications of sisal fibers, making them more viable for use in sustainable textile production in future

Keywords: Sisal fibers, Alkali treatment, Reactive dyes, Vat dyes, Colorfastness

Design, Fabrication and Performance Evaluation of Parabolic and Enhanced Solar Box Cookers in Isimani, Tanzania

Margaret E Samiji — 2024-10-02

Clean cooking energy is a global priority, especially in developing countries where firewood and charcoal remain the primary cooking fuels. Solar cooking is an attractive alternative in these countries since it is eco-friendly and utilises freely available solar radiation. Utilisation of solar cookers however is still very low mainly due to the perceived complexity and lack of confidence in the available solar cooker models. In this work, the enhanced box and parabolic solar cookers were designed, fabricated and tested taking into consideration standard solar cookers and local cooking requirements. The enhanced box solar cooker was designed with booster mirrors making an effective aperture area of 0.68 m², a double glass glazing and a glass wool insulator between the double walls of the cooking box. The parabolic cooker was designed with polished aluminium paraboloid with a net aperture area of 1.44 m², a parabola depth of 0.47 m and manual solar tracking. In field tests in Isimani Tanzania, the enhanced solar cooker attained a maximum temperature and cooking power of 129.8 °C and 101.9 W, respectively, and was able to boil 2 litres of water in 100 minutes. The parabolic cooker on the other hand registered a maximum cooking power of 513 W at solar noon and was able to boil 2 and 5 litres of water in reasonable times of 30 and 60 minutes, respectively.

Keywords: Clean cooking, parabolic solar cooker, enhanced box solar cooker, polished aluminium, cooking power

Multi-criteria Analysis of Municipal Solid Wastes Treatment Scenarios: The Case of Arusha City, Tanzania

Edwin N. Richard — 2024-10-02

Selection of the most effective municipal solid waste (MSW) treatment option is crucial for sustainable MSW management, but it remains a challenge in most cities of developing countries. More often, the decision-makers make the selection of the treatment options without economic (ECs), and environmental (ENCs) cost evaluations. Consequently, the selected technologies fail to suit the local conditions of the concerned areas and they become a high burden activity to manage. Therefore, this study aimed to use the multi-criteria analysis approach based on the ELECTRE method to analyse the most effective MSW treatment option in terms of ECs and ENCs costs in Arusha City Tanzania. A study involved the design of 54 treatment scenarios and identified six initial acceptable scenarios for ELECTRE analysis. The ELECTRE analysis results indicated that the scenario which suggests the use of composting options for organic wastes, recycling options for glass, metals, paper and plastic wastes and the use of a landfill for other wastes emerged as the dominant scenario. This scenario had the daily ECs of US$11,178 while avoiding about 124 tons of CO₂ emissions daily. A sensitivity analysis results with different criteria weights also indicated the selected scenario outranked other alternatives. The findings from this study can be applied by the decision-makers to improve MSW management in study areas and cities with similar MSW conditions.

Keywords: Municipal solid wastes; Multi-criteria; ELECTRE; Treatment option; Arusha

Advanced Principal Component Analysis of Various Risk Factors of Hepatitis B Prevalence in Nigeria

Nureni O. Adeboye — 2024-10-02

Hepatitis B virus (HBV) is an infectious disease globally estimated to have caused between 500,000 to 1.2 million deaths annually. HBV prevalence is still high in Nigeria. Thus, this research aimed to identify factors germane to the widespread of HBV infection in an apparent clinical survey. The methods of analysis used were frequency, percentage and Principal component analysis (PCA). This was achieved through hospital record extracts of consultant hepatologists and the dimensionality reduction of the acquired data while retaining essential factors that are germane to the prevalence of HBV infection. The findings revealed that out of seventeen components evaluated in the study, the PCA retained 15 components of which Eigen-values are greater than 1.00. The symptoms retained in every component were fever, muscle pain, fatigue, loss of appetite, blood in vomit, jaundice, pale stool, nausea, blood in faeces, weight loss, malaise, abdominal pain, joint ache, swollen of lower extremities, confusion and yellow eye. The symptoms were listed in accordance with their level of relevance for diagnosing HBV in patients, and all the variables retained accounted for 94.278% variation in the prevalence of HBV infection, with the majority of the infected populace found among the adults (18 -64 years).

An Age-Structured Model for the Effects of Temperature and Rainfall on the Transmission Dynamics of Malaria

Alanus Mapunda — 2024-10-02

This study has investigated the impact of temperature and rainfall on the transmission dynamics of malaria using an age-structured population model, with a class of pregnant women. The equilibrium solutions have been analyzed, and numerical simulations carried out. The results show that there are significantly high rates of malaria infections for the temperature and rainfall ranging between (23.53 ⁰C − 39.80 ⁰C) and (14.82 mm − 38.44 mm) respectively. The results have shown that, the most affected populations are children up to five years old and pregnant women, and that decreasing the rate of transplacental transmission increases the number of children born free of malaria infections. Therefore, this work recommends human individuals to be aware of the variations of temperature, rainfall, and their corresponding ranges at which malaria transmission occurs most, so that they can take precautions.

Age-structure; Pregnant women; Temperature and rainfall; Malaria dynamics; Transplacental transmission

Nesting of an Alien Invasive House Crow Corvus splendens in Verges along Arterial Roads in Dar es Salaam, Tanzania

Jasson R. John — 2024-10-02

In most cities where little of the original natural vegetation remains, road verges act as home to many urban wildlife. However, the use of road verges for alien avifauna such as House Crow (Corvus splendens) has not been fully documented. This study, conducted between June and July 2021 investigated nesting preferences of the House Crow with particular regards to different verge subdivisions of arterial roads and tree species in Dar es Salaam, Tanzania. Nests were searched in 1813 trees (=42 species) along a stretch of 20 km, and 159 trees (=15 species) were nested with C. splendens. Overall, a total of 257 nests were found on site of which 127 were active. The mean number of nests per tree crown did not vary significantly among the road subdivisions. Nests were positioned between 4 and 16 m above ground in trees with 7.71±2.56 m canopy spread and a mean height of 9.97±2.28 m. For nesting, three tree species were dominant, eight were common, and 31were rare. However, majority of the tree species with the highest nest use ratio were not dominant indicating nesting preference. It is therefore important to consider the influence of tree species on the population of the House Crow during planning for urban verge development. Additionally, managing tree crown is among the best practices to discourage House Crow nesting in urban road verges.

Evaluation of therapeutic efficacy of Aloe rabaiensis leaf against Salmonella gallinarum challenged in Kuroiler chicks in Arusha, Tanzania

Mwanaisha S. Mkangara — 2024-10-02

Salmonella gallinarum, a bacterium causing fowl typhoid in gallinaceous birds, poses significant economic challenges to the chicken industry in Tanzania. This study investigated the potential of Aloe rabaiensis in managing S. gallinarum in Kuroiler chicks. The clinical signs, viable cell count, live weight, heterophils, lymphocytes, and monocyte counts were evaluated using ninety-four chicks grouped into T1, T2, T3 (challenged with S. gallinarum), and T4 (unchallenged with S. gallinarum). The findings revealed no statistically significant differences between the treated and control groups (P > 0.05) in viable cell count, live weight, mortality rate, heterophils, lymphocytes, and monocyte counts. However, there were clinical signs of fowl typhoid in the challenged groups (T1, T2, T3). The groups challenged with S. gallinarum and treated with A. rabaiensis (T1, T2) showed reduced susceptibility to the bacteria compared to the control group, T3. The mortality rate for T1 was 14.3% (4, n=28) and T2 17.9% (5, n=28), while the control group T3 was 25% (7, n=28). The lower mortality rates and less severe fowl typhoid symptoms in the Aloe-treated groups were attributed to the antibacterial efficacy of A. rabaiensis leaf against S. gallinarum, offering a promising remedy for the future of poultry health.

Natural Bee Space and Comb Cell Dimensions of Honey Bee Colonies in Mwinkantsi Village, Babati District, Tanzania

Theobald J Theobald — 2024-10-02

The use of improved beehives in beekeeping is emphasized to facilitate easier colony manipulations. The improved beehives used in Tanzania are either imported or manufactured locally by adopting dimensions for European honey bees. However, the dimensions adopted are faulty to the dimensions of local honey bees, leading to cross-combing problems which hinder realization of the expected management advantages. This study assessed the characteristic natural bee space and comb cell dimensions of honey bee colonies occupied the traditional split log hives in Mwinkantsi village, Babati district. Results showed that honey bee colonies in Mwinkantsi village exhibited an overall bee space of 11.82 ± 0.36 mm, larger than a range of 7.5 ± 1.5 mm bee space reported for European honey bees. The colonies also exhibited 22.21 ± 0.62 mm overall average comb thickness, 12.01 ± 0.57 mm comb cell depth, and 5.05 ± 0.46 mm comb cell width. Moreover, both bee space and cell dimensions showed significant variations influenced by comb type. These findings add to the body of knowledge and suggest extensive agroecological investigations on natural characteristic dimensions of local honey bee colonies in Tanzania. This will inform the construction of improved hives that suit local honey bee colonies.

Keywords: Honey bees; Bee space; Comb thickness; Cell dimensions; Tanzania.

Antibacterial Activity and Phylogeny of Griseofulvin Producing Aspergillus and Penicillium Species from Kunduchi Mangrove Sediments, Tanzania

Blandina A. Mavoa — 2024-10-02

Marine fungi are an underrated reservoir of bioactive metabolites for drug discovery. This study focused on fungi isolated from Kunduchi mangrove sediments in Tanzania. In an attempt to investigate the antibacterial activities of marine fungi and uncover their bioactive compounds, ethyl acetate crude extracts of fungal isolates were screened for antibacterial activity against human pathogens (Bacillus subtilis, Staphylococcus aureus and Escherichia coli) followed by compounds identification by Gas Chromatography-Mass Spectrometry (GC/MS). A total of seven fungal isolates were obtained from sediments. Crude extracts from isolate 1 and isolate 2 exhibited significant antibacterial activities with a Minimum Inhibitory Concentration ˃ 3.13 mg/ml against S. aureus and MIC ˃ 0.78 mg/ml for both B. subtilis and E. coli. Furthermore, crude extract analysis by GC/MS detected a substantial amount of griseofulvin from the extracts of both isolates 1 and 2. Using nuclear Large Subunit and Internal Transcribes Spacer molecular markers, griseofulvin-producing fungi were identified as Penicillium aethiopicum and Aspergillus sydowii. Significantly, this marks the first documented instance of griseofulvin production by A. sydowii from the marine environment worldwide. Our research has not only identified a new alternative source of griseofulvin from A. sydowii but also underscores the importance of optimizing culture conditions to enhance the production of bioactive metabolites by the identified mangrove-derived fungi. Future studies may prioritize on optimization of culture conditions as it could have significant implications for the pharmaceutical industry and the development of novel antibacterial agents.

Keywords: Antibacterial activity; Griseofulvin; Human pathogens; Mangrove sediment fungi.

Vegetation invasion influences waterbird assemblages and aquatic environmental parameters in urban areas of Dar es Salaam, Tanzania

Daudi O. Damas — 2024-10-02

Waste Stabilisation Ponds (WSPs) serve as refuge habitats for waterbirds in response to the decline of natural wetlands especially in urban settings. Various sewage treatment stages within WSPs attract waterbirds differently based on the specific characteristics of each stage. This study examines the influence of treatment stages on both vegetated and non-vegetated WSPs over a period of one year in Dar es Salaam, Tanzania. Bird surveys were periodically conducted at each treatment stage along with different environmental variables; dissolved oxygen, electrical conductivity, water turbidity, water temperature, pH, and invertebrate biomass. In non-vegetated WSPs, waterbird densities and invertebrate biomass were significantly higher in facultative ponds than in maturation ponds (p < 0.05). The water pH was higher in maturation ponds than in facultative ponds (p < 0.05). However, in vegetated WSPs, no notable variations in waterbird density and environmental variables were observed across different treatment stages (p > 0 .05). The presence of vegetation in WSPs created similar environmental conditions across treatment stages, potentially reducing waterbird preferences for specific stages. These findings underscore the importance of understanding the characteristics of sewage treatment stages in order to enhance the management of WSPs as suitable habitats for waterbird populations in urban areas.

Forest Management Optimization Scenarios for Climatic and Economic Benefits Generated from Tectona grandis Plantation in Muheza, Tanzania

Omari S. Mgoo — 2024-10-02

Globally, multiple ecosystem services are increasingly becoming an important agenda in sustainable forest management. However, it is still unclear which forest management practices would lead to an optimal bundle of ecosystem services promoting sustainability. This study aimed to determine whether implementing thinning schedule and 30 years rotation age has implications on the provision of ecosystem services and economic benefits of Teak stands in Tanzania. Carbon quantification and cost-benefit analysis methods were used to study the climatic and economic benefits of wood production and carbon sequestration under five scenarios where three thinning schedules and 30 years rotation age were the baseline. Data were collected from 168 purposively selected circular plots of radius 9.78 m distributed systematically in 9 thinned stands. Thinned stands were implemented with intensities of 50%, 50%, and 25% in first, second, and third thinning respectively. Results showed that decreasing 33.4% rotation age from baseline while maintaining three thinning schedules maximized climatic and economic benefits of combined wood production and carbon storage goal by 181.5%. Preferred thinning schedules and rotation age had wood production and carbon sequestration of 821 m³/ha and 41.3 t/ha respectively. Managing Teak Forest plantation for the combined goal of wood production and carbon sequestration is recommended.