Tanzania Journal of Science

Finite Element Models for Predicting Moisture Effects on Bolt Embedment and Connection in Timber

Henry Meleki Kiwelu — Tue, 31 Dec 2024 00:00:00 +0000

The mechanical performances of timber connections are particularly important for timber engineers involved in the design of the wood structures. The mechanism of connection must be well understood in order to design a safer connection and avoid catastrophic failure. Often connections are made weak fuse elements by deliberate intent to ensure that if structural systems fail it will be by controllable ductile deformation of connections in load paths. Model method of determining engineering design capacities of laterally loaded dowel fasteners, such as bolts, screws and nails was developed. It should however be pointed out that FE and similar continuum model results always over predicted capacities at particular levels of deformation relative to experimental values. This result was expected and reflects the well-known inability of such models to incorporate all energy sinks that exist in experiments. The primary findings of the work reported is that it is highly viable to predict even complex effects that treatments like post-fabrication moisture conditioning have on responses of bolted glulam connections. Uniqueness of what is presented lies in the analysis of the combined influences of moisture content and mechanical loads by numerical methods. This makes such models viable means of supplementing physical test data and analyzing of highly complex timber connection situations.

Geochemical Characterization of Hydrocarbon Source Rocks in the Jurassic – Cretaceous Ruvu sub-basin- within the Coastal Basin of Tanzania; Implications for Petroleum Prospecting

Hadija H Maumba , Charles H Kasanzu — Tue, 31 Dec 2024 00:00:00 +0000

In this study, we characterize hydrocarbon source rocks from the Ruvu sub-basin’s Kiwangwa well-1 using organic matter, total organic carbon (TOC), rock-eval pyrolysis and vitrinite reflectance data. Analytical results indicate fair to excellent TOC contents in the sub-basin, a feature suggesting conditions that favor organic matter production and preservation. Kerogen types II to IV are inferred for the Kiwangwa well-1 sediments. Using TOC vs S₂for the Early Jurassic and Triassic of Kiwangwa well -1 at depth intervals, good to very good source rocks are inferred. This suggests high generative organic matter suitable for hydrocarbon production. None generative organic matter window is inferred for the Cretaceous, Middle Jurassic and Late Jurassic time intervals in the sub-basin. Generation potentiality of the source rocks employing the HI and TOC parameters show that the Late Jurassic source rocks interval in the Ruvu sub-basin are gas or oil-prone. Our findings from generation potentiality in the study area indicate that the Late Jurassic source rock interval in Ruvu can offer guidance for potential prospects and gas-exploration targets. Evaluation of the degree of thermal evolution of the sedimentary organic matter using vitrinite reflectance and production index suggest marginally matured source rocks for the Late Jurassic – Middle Jurassic that indicate reworked particles.

Assessing the Variability of Heavy Rainfall Events during Gu Rainfall Season in Somalia

Abdinasir Elmi, Paul TS Limbu — Tue, 31 Dec 2024 00:00:00 +0000

The occurrence of heavy rainfall is a significant contributing factor to the occurrence of flooding in Somalia during the rainy season, resulting in substantial socio-economic consequences. This study investigates the spatial-temporal variations of Heavy Rainfall Events (HREs) occurring from March to May (MAM), commonly referred to as the Gu rainy season, in Somalia from 1991 to 2020. The analysis employed the Empirical Orthogonal Function method to investigate the spatial-temporal variations of HREs. The findings indicate that there is an unequal distribution HREs throughout the country, with the southern regions exhibiting the highest concentration of HREs of about 340 HREs, while the northwestern regions had a relatively lower number of HREs. It was found that there is a notable variation in HREs on a monthly basis, with April and May exhibiting a higher prevalence compared to March, which appears to have a lower impact. The prevalence of HREs has been seen to be more prominent and rapidly escalating, particularly in the southern region, with a statistically significant level of 95%. Moreover, it has been found that the recurrence rate of HREs in the southern region of the country is around once every decade, whilst in the central region, the average return time of HREs is three years. Conversely, the northern region experiences HREs on an almost annual basis. Therefore, it is imperative to comprehend the spatial and temporal variations of heavy rainfall in order to effectively strategize agricultural practises and implement mitigation measures for extreme weather phenomena such as droughts and floods.

Rainfall Variability; Heavy Rainfall Events; Gu Rainfall Season; Somalia

Spatio-temporal Trends and Change Detection of Surface Air Temperature in Tanzania: October to April Season.

Laban Lameck Kebacho, Exavery Kisesa Makula, Paul Tilwebwa Shelleph Limbu — Tue, 31 Dec 2024 00:00:00 +0000

The paper examined the spatio-temporal variability and trends of minimum temperature (T-min), mean (T-mean), and maximum temperature (T-max) in Tanzania from October to April using the Climatic Research Unit Time Series version 4.06 from 1951-2021. The traditional Mann-Kendall (MK) test, modified MK, and Sen’s slope test were used to determine the trend direction and magnitude of the T-mean, T-max, and T-min trends, respectively. Sequential MK, standard normal homogeneity, and Pettitt tests were used to detect abrupt changes, while the Hurst coefficient (H) assessed future trend behavior. Results show a statistically significant increasing trend of 0.14 °C per decade, 0.18 °C per decade, and 0.16 °C per decade in T-mean, T-max, and T-min, respectively, at a 95% confidence level. The H values of T-min, T-max, and T-mean are above 0.7, indicating their future increasing trends. The change points for T-mean and T-max were in the early 1990s, and for T-min in the late 1990s. After 1991, more locations showed significant trends (positive or negative) for T-max than T-mean, and T-min had no significant trend after 1998. The 1960s had the lowest T-max and the 2010s had the highest T-min. Therefore, this study provides valuable information for immediate planning and future climate monitoring in Tanzania.

Design and Optimization of Eco-Friendly Biocomposite Films for Packaging Applications Using Response Surface Methodology

BA Omoike, FE Okieimen, C Imoisi — Tue, 31 Dec 2024 00:00:00 +0000

The use of synthetic polymers as packaging materials constitutes environmental pollution due to the accumulation of plastic waste after they are discarded. This study aimed at preparing and optimizing an environmental-friendly carboxymethyl starch/PVA/kaolin composite film using response surface methodology to develop potential solutions for replacing synthetic packaging and optimize the formulation of the biocomposite films. The biocomposite films were prepared by solution casting method. The interactive effect of carboxymethyl starch (CMS) (2.0-5.0 g), poly(vinylalcohol) (PVA) (0.0-3.0 g) and kaolin (0.00-0.22 g) on the ultimate tensile strength (UTS), percentage elongation at break (%EB) and water vapour permeability (WVP) were determined. The central composite design (CCD) was used to optimize the compositions of the composite films to yield best properties. The results showed that the interaction of PVA and kaolin with the carboxymethyl starch had a positive increasing effect on the tensile mechanical and barrier properties of the composite films. The optimal compositions of the composites obtained at 95.4% desirability were 3.33 g CMS, 2.39 g PVA and 0.22 g kaolin. Also, the predicted optimal values of the ultimate tensile strength, %EB and WVP of the composites were 5.71 MPa, 23.57% and 1.08 g/m^.s.Pa.

Carboxymethyl starch; Biocomposite; Water vapour permeability; Response surface methodology; Tensile mechanical properties

Optimizing CO2-expanded Hexane for Enhanced Yield and Antioxidant Activity of Essential Oils from Citrus reticulata

Mathayo Gervas Mathias, Idzumi Okajima — Tue, 31 Dec 2024 00:00:00 +0000

Wide range applications of citrus essential oil (EO) and environmental issues resulting from citrus processing industries render in the evolution of extraction techniques. The efficacy of the CO₂-expanded hexane (CXH) extraction technique on mandarin orange EO, D-limonene, and total phenolic compounds (TPC) was evaluated and compared with conventional methods; hexane extraction and hydro-distillation. Moreover, the correlation of EO components with antioxidant activity was studied. It was revealed that CXH had better EO and D-limonene yields than conventional methods. The CXH optimal extraction conditions of 25 °C, 6.5 MPa, and 0.70 CO₂ mole fraction offered 0.155 g-EO/g-dry peel and 51% D-limonene in EO. Less total phenolic compounds and phospholipids were extracted using CXH compared to hexane extraction. However, a similar inhibition capability (12–54%) of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radical was obtained regardless of the extraction technique. In addition, DPPH scavenging activity depended on the TPC composition. The results suggest the potential application of CXH for citrus waste valorization.

Assessment of Reactive Dyeing of Cotton using Seawater

Liberato V Haule — Tue, 31 Dec 2024 00:00:00 +0000

This study investigated the effects of auxiliary chemicals on reactive dyeing of cotton fabric using seawater as an alternative to freshwater. The study involved dyeing of 100% cotton fabric with reactive blue 21 using both fresh and seawater. The effects of Na₂SO₄, NaCl and Na₂CO₃ auxiliaries were assessed on dye exhaustion, fixation and colour strength. Reactive dyeing using seawater with a pH 9 which contained Na⁺ (882.4 mg/L), Cl^- (938 mg/L), Ca²⁺ (1200 mg/L), CO₃^-2(3000 mg/L), Mg²⁺(1030 mg/L) and alkalinity (4615 mg/L), resulted in exhaustion rate of 54%, colour strength of 0.098 and fixation rate of 44%. While dyeing using freshwater gave exhaustion rate of 34%, colour strength of 0.026 and fixation rate of 34%. When auxiliaries were added, the exhaustion, colour strength and fixation for freshwater dyeing were 66%, 0.199 and 84%, respectively. In contrast for seawater dyeing, the corresponding results were 56% for exhaustion, 0.53 for colour strength, and 76% for fixation. These results showed that seawater’s natural electrolytes reduced the need for additional chemicals but also led to excessive auxiliary concentrations that hindered dye performance. Freshwater dyeing, by contrast, showed higher dye exhaustion, colour strength, and fixation when auxiliaries were added. Given the rising demand for freshwater and the high-water consumption in textile dyeing, particularly with reactive dyes, the seawater could be a viable substitute. Therefore, seawater is a feasible alternative for textile dyeing, provided chemical adjustments are made to optimize dye exhaustion and fixation.

A Comparative Study of Unfolding Techniques for Gamma-Ray Spectra Obtained with NaI(Tl) Scintillation Detectors

Mwingereza J Kumwenda — Tue, 31 Dec 2024 00:00:00 +0000

Iterative unfolding methods are frequently used in acquiring true gamma-ray spectra from the measured spectra. However, the peak resolution of iterative unfolding methods especially, in Gold algorithm method is very challenging, especially in the case of scintillation detectors, where several instrumental artifacts and distortions interfere with the true spectral shape. Therefore, this paper presents a comparative study of the direct matrix inversion unfolding method (DMIUM) and iterative unfolding method with emphasis on the Gold algorithm method (GAM) in converting measured gamma-ray spectra of the NaI(Tl) scintillation detector into the true gamma-ray spectra. The Monte Carlo simulation based on the Geant4 software package was used to study the response function of the NaI(Tl) scintillation detector and for the formation of 200 by 200 response matrices. The results obtained from the number of the integrated photon counts of gamma-ray energies of 662 keV, 1173 keV, and 1333 keV respectively, for the DMIUM were 4, 91, and 93 times greater than in the original energy spectrum while for the GAM method were 3, 14, and 4 times greater than in the original energy spectrum. In conclusion, these results suggest that DMIUM is better in peak resolving ability than the GAM.

Single-step sol-gel synthesis of CuO/TiO2 nanoparticles: Microstructure and materials characterization

Godlisten N Shao — Tue, 31 Dec 2024 00:00:00 +0000

Copper oxide modified titanium dioxide (CuO/TiO₂) nanoparticles have been widely reported owing to their excellent performance in heterogeneous photocatalysis. However, their industrial and large-scale production is hampered by tedious and expensive preparation methods. The present study presents a single step sol-gel synthesis of CuO/TiO₂ nanoparticles with improved physicochemical properties. A series of CuO/TiO₂ nanoparticles were synthesized by a modified sol-gel approach using titanium oxychloride as a TiO₂ precursor in the absence of additives. The samples were examined by high-resolution TEM, SEM-EDAX, XRD, XRF, XPS, Raman spectroscopy, nitrogen gas physisorption studies, and UV-visible DRS analyses. It was found that the proposed method facilitated the formation of CuO/TiO₂ nanoparticles with superior morphology, crystal structure and optical properties. XRD results showed that the introduction of Cu²⁺ into TiO₂ microstructure delayed the anatase to rutile phase transformation in the calcined samples. Hence, samples with pure anatase phase, pure rutile phase or a mixture of anatase and rutile TiO₂phases were exquisitely yielded. The band gap energy of the TiO₂ was reduced from 3.14 eV to ~ 2.0 eV due to the presence of CuO. Therefore, the present study provides a convenient method to yielding sol-gel synthesized CuO/TiO₂ with improved physico-chemical properties in the absence of additives.

Uncertainties in Measuring Lifetimes of Nuclear Excited States using a Fast Electronic Timing System made of NaI (Tl) Scintillators

Innocent J Lugendo — Tue, 31 Dec 2024 00:00:00 +0000

Measurements of the lifetimes of nuclear excited states need to be as accurate as possible due to their crucial role in making or verifying various theoretical predictions in the nuclear science and astrophysics. Nevertheless, metrological difficulties in these measurements have brought about controversies that significantly influence the quest to understand the atomic structure, decay processes and nuclear reactions. Among the obstacles are the accuracy and precision of the systems and techniques used for measuring the lifetime of an excited state. It follows that any hypothesis regarding the nuclear behavior can only be considerable upon verification and accountability of stability and uncertainty of the devices used during the experiments for measuring the lifetime of a nuclear excited state. As a step towards accurate measurements of lifetimes of excited states, this work focuses on evaluating the uncertainties of such measurements. In doing so, a fast timing system made of two NaI(Tl) detectors have been developed to measure the lifetime of the 5/2+ excited state of ¹³³Cs using the gamma-gamma coincidences. An uncertainty budget showed the sources of uncertainties in measuring the nuclear excited state’s lifetime include timewalk, drift effect, selection of the region of interest, background effects and counting statistics. The total uncertainty in measuring the 5/2+ excited state of ¹³³Cs was found to be 0.024 ns, representing 0.382% of the nominal lifetime value. This implies that the system can accurately measure the lifetimes of excited nuclear states ranging from 1 ns.

Modelling the Effects of Antiretroviral Therapy on Kidney Diseases Among HIV Infected Individuals in Tanzania

Janeth Pancras Mchwampaka, Eunice Mureithi, Nyimvua Shaban Mbare — Tue, 31 Dec 2024 00:00:00 +0000

This study examined the role of highly active antiretroviral therapy (HAART) in the dynamics of kidney diseases among HIV-infected individuals. A deterministic model was formulated for the dynamics of kidney disease in HIV-infected people with HAART as treatment in the model. Numerical simulations showed that though HAART reduces HIV progression to the AIDS stage, there is an increase in HIV-related kidney diseases. Also, the result obtained in this study showed that reducing the effective contact rate of HIV and improving the effectiveness of HAART by 99% in preventing the progression from HIV without symptoms group to HIV-related kidney diseases can decrease the prevalence of HIV-related kidney diseases. Therefore, based on the findings obtained to reduce the population of HIV-related kidney diseases in the general population Pharmacists should focus on improving HAART which will reduce the progression of kidney diseases from HIV.

Mathematical Analysis of Monkeypox Transmission Dynamics with Control Strategies

Singo Juma Singo, Furaha Michael Chuma, Zubeda Seif Mussa — Tue, 31 Dec 2024 00:00:00 +0000

This study develops a mathematical model to analyze the transmission dynamics of Monkeypox and evaluate the effectiveness of control strategies. The model is formulated as a system of nonlinear differential equations, capturing key factors such as human-to-human transmission, zoonotic reservoirs, and control measures like vaccination, culling, personal hygiene and treatment. The model's equilibrium points, including the disease-free and endemic equilibria, are determined and analyzed for stability using the effective reproduction number, . Conditions under which ensure the elimination of Monkeypox, while indicates sustained transmission. A sensitivity analysis is performed to identify parameters that significantly influence , such as the contact rate, effectiveness of control measures, and the rate of recovery. Numerical simulations demonstrate the impacts of individual control strategies such as vaccination, treatment, culling, and personal hygiene when applied alone. All of the control shows positive impact on the disease prevalence. This analysis provides critical insights for optimizing resource allocation and improving public health responses to Monkeypox outbreaks. The findings underscore the importance of timely and effective implementation of control measures to curb the spread of Monkeypox and mitigate its public health impact.

Analysis of Unsteady Convective Boundary Layer Flow with Magnetic fields, Chemical reaction, Thermal Radiation and Variable fluid Properties

Jonas A. James, Makungu J. Ng’oga, Augustino I. Msigwa, Ali A. Omary — Tue, 31 Dec 2024 00:00:00 +0000

This study extends the previous work by Kitengeso et al. (2018) by investigating unsteady convective boundary layer flow, incorporating magnetic fields, chemical reactions, radiation, and variable fluid properties over the inclined plate. The boundary layer and Boussinesq approximations are used to derive the magnetohydrodynamic flow equations. Thereafter, the equations are transformed into similarity form using similarity variables and then solved using the 4^thorder Runge - Kutta method. The key parameters such as the magnetic parameter, chemical reaction rate, variable fluid properties, unsteadiness, convection, and radiation parameter significantly affect flow behavior over an inclined plane. It was found that increasing the magnetic field strength enhances the fluid velocity, temperature, and concentration. Additionally, an increase in the unsteadiness variation parameter within the boundary layer leads to higher velocity and concentration while reducing temperature. Conversely, the fluid temperature and concentration decrease as the chemical reaction parameter in the boundary layer rises. Furthermore, an increase in the magnetic parameter results in increase in the heat transfer rate while simultaneously decreases the skin friction and mass transfer rates. Also, the fluid temperature decreases as radiation parameter increases.

Antioxidant Potential of Stingless Bee Honey from Mangrove and Montane Vegetation Types in Tanzania

Christopher Alphonce Mduda, Mkabwa Lawrence Katambo Manoko — Tue, 31 Dec 2024 00:00:00 +0000

Stingless bee honey is a rich source of antioxidants and is highly regarded in traditional medicine for the treatment of various ailments. The antioxidant capacity of honey can be influenced by its origin and the floral resources used by bees. Consequently, this study evaluated the antioxidant potential of stingless bee honey from two vegetation types: montane and mangrove. The honey samples displayed remarkable antioxidant potential, with notable levels of total phenolic content (197.0–263.1 mg GAE/100 g), total flavonoid content (118.5–156.7 mg QE/100 g), ascorbic acid (25.1–30.0 mg/100 g), lycopene (2.8–3.7 mg/100 g), β-carotene (0.8–1.7 mg/100 g), DPPH (2,2-diphenyl-1-picrylhydrazyl) scavenging activity (68.5–73.6%), and ferric reducing antioxidant power (265.9–272.7 µmol Fe(II)/100 g). Notably, the antioxidant properties varied between vegetation types, with mangrove honey exhibiting significantly higher levels of total phenolic and flavonoid content (p < 0.01). These results underscore the therapeutic potential of stingless bee honey for managing oxidative stress and the associated diseases.

Effect of Alternative Rearing Substrates on the Growth, Reproduction and Nutritional Composition of the African Field Cricket Gyrllus bimaculatus (Orthoptera: Gryllidae)

Atujune Katabaro, Blanka Joseph, Anitha Philbert — Tue, 31 Dec 2024 00:00:00 +0000

The increasing demand for animal protein to cater to the ever-growing human population has prompted the quest for alternative protein sources from insects. The field cricket Gyrllus bimaculatus, is one of the species of major interest, however, rearing of this species depends on the commercial chicken feed, which is expensive. This study explored the suitability of food remains in the rearing of this species. Three experimental food types were formulated from various food remains, and fed to crickets along with the commercial chicken feed for 14 weeks. Crickets that were fed on a combined diet of mixed food types performed better in terms of growth, biomass, and survivorship than their counterparts. Food types had a significant effect on the growth rate of the crickets, crickets that were fed on combined diet of mixed food types had the highest average weight of 405.70 ± 1.71 mg, whereas, crickets that were fed on the control diet had an average weight of 284.7±5.03 mg. Analysis of the nutritional composition of the harvested crickets yielded similar results of crude protein contents for crickets that were fed on control diet and combined diet with 54.70% and 50.70 % crude protein contents, respectively. Since the performance of crickets that were reared on locally available food remains was similar to the ones that were fed on a standard commercial diet, this simple diet presents a potential substrate for mass rearing of crickets which is cost-effective.

Impact of Helminth Co-Infections on Clinical Malaria Severity Among Febrile School-Age Children: A Study from Mvomero, Tanzania

Winifrida Kidima, Christopher Kisiringo, Deokary Matiya , Felista Mwingira — Tue, 31 Dec 2024 00:00:00 +0000

Helminths may influence clinical malaria severity. The current study examined the impact of helminth infections on malaria severity among children in Mvomero, Tanzania. This was a hospital-based cross-sectional study conducted from 2018-2019. Blood, stool and urine specimens from febrile subjects attending four health facilities in Mvomero were examined for malaria and helminth infection. Overall, 326 febrile children were enrolled. The range and mean ages were 5-17 and 10.2 years, respectively. Of 326 children, 46.8% (n = 153) had Plasmodium falciparum malaria, with prevalence being higher in males than females (p = 0.03). Among positive P. falciparum -infected children, 59.5% had malaria alone, and 40.5% were co-infected with helminths. Schistosoma haematobium was the most common parasite in malaria-positive children (p = 0.04), with the highest prevalence amongst the 11-13-year-olds (18.3%, p = 0.02). The prevalence of anemia among malaria malaria-positive individuals was 28%. Anemia was more common in children between 8 -10-year-old (p = 0.013). Malaria-positive children co-infected with hookworm and haematobium exhibited a reduced mean Hb concentration and an increased P. falciparum parasitaemia ( p < 0.05). To conclude, co-infection with hookworm and schistosoma increases the severity of clinical malaria. An integrated malaria and helminth management strategy for all individuals in Mvomero is crucial.

Cytotoxicity of Heliotropium indicum Methanolic Leaf Extract in Mice

Claudius D Luziga, Benedictor J Jagadi, Jackson A Ngou, Frida R Mgonja — Tue, 31 Dec 2024 00:00:00 +0000

Heliotropium indicum grows well in wet fertile soils often near rivers and lakes in tropical and subtropical countries. It contains phytochemicals with beneficial health effects. However, information is scarce on its cytotoxicity. The objective of this study was to determine cytotoxic effects of methanolic leaf extract of the plant in mouse organs. Mice were randomly divided into four groups: Control group A received distilled water 10 ml/kg. Groups B, C, and D received orally plant leaf extract at doses of 5 mg/kg, 10 mg/kg, and 15 mg/kg respectively per day for 7 days. At the end of day 7 mice were sacrificed, tissues from various organs dissected, processed into tissue blocks and sectioned followed by Haematoxylin and Eosin staining to examine histological organization of the tissues and immunohistochemical analysis for single stranded DNA (ssDNA) to determined cell death by apoptosis. The results showed that the extract at all doses in both male and female mice induced cell death. Affected cells include spermatogonia in testis leading to absence of spermatozoa in seminiferous tubules; stromal cells and cumurus oophorus of the ovary, epithelial cells lining glandular and non-glandular stomach; hepatocytes of the liver, collecting ductal cells in medullary rays in the kidney, pneumocyte type I, II and macrophages of the lungs and cells of red and white pulps of the spleen. It can be concluded that methanolic leaf extract of H. indicum is cytotoxic to cell of the vital organs of the body, suggesting that medicinal use of the plant leaf extract in any form should be taken with care.

Mouse; body organs; apoptosis; traditional medicine

Metagenomic Analysis of Bacterial Communities in Waters of Lake Natron, Arusha, Tanzania

Sadikiel E. Kaale, Robert S. Machang’u, Thomas J. Lyimo — Tue, 31 Dec 2024 00:00:00 +0000

Metagenomics involves genetic material extraction and sequencing directly from environmental samples in order to gain insights and relationships that exist between microbes and their surroundings. Few studies have been done in extreme environments including soda lakes such as Lake Natron which is found in Arusha region, Tanzania. This study recorded high pH and salinity values confirming the lake's extremity. Full-length 16S rRNA reads sequenced through PacBio was used to reveal first metagenomic snapshots of bacterial communities from 10 random points at the lake shoreline waters. The results showed the dominance of Proteobacteria and Firmicutes with relative abundances of 98.46% and 70.46, respectively. Alphaproteobacteria (93.59%), Bacteroidia (23.80%) and Bacilli (23.19%) were the most dominant classes. Oceanibaculaceae (52.43%), Rhizobiaceae (66.62%) and Izemoplasmataceae (12.50%) were the most dominant families. The dominant genera were Oceanibaculum (52.44%), Allorhizobium (65.59%) and Izimaplasma (12.50%), respectively. The diversity indices showed high level of community diversity, a large number of species, the presence of rare species and an even distribution of bacteria across the sampling points. While this study provides the first report on the occurrence of various taxa in Lake Natron, functional metagenomic analysis is recommended for further investigation of the ecological and biotechnological significance of the identified species.

Metagenomics; PacBio sequencing; bacteria diversity; Soda Lakes; Lake Natron

Length-Weight Relationship and Condition Factor of Three Cichlids from the Tono Dam, Ghana

Tue, 31 Dec 2024 00:00:00 +0000

The length-weight relationship (LWR) and condition factor of three Cichlids, namely, Sarotherodon galilaeus, Coptodon zillii and Oreochromis niloticus from the Tono dam in Ghana, were investigated. A total of 1,870 individuals of the target species were randomly collected from 20 artisanal fishermen using gill nets to fish from January to December 2015. Each species was sorted by sex, and each fish's total length (L) and body weight (W) were measured and recorded. Simple linear regression plots of weight against length were computed, and the slope of the regression line, ‘b’ and intercept of the regression line, ‘a’ of each species (male, female, and mixed sexes) were derived. Their condition factor (K) was estimated using the relationship, K = 100W/L³. The total length and body weight of the three species ranged from 5.0 - 21.5 cm for O. niloticus, 2.1 - 19.5 cm for S. galilaeus, and 4.5 - 19.5 cm for C. zillii, while their body weight ranged from 08.0 - 282.0 g for O. niloticus, 10.0 - 270.0 g for S. galilaeus and 10.0 - 210.0 g for C. zillii. All three species exhibited a positive allometric growth pattern, except for females of S. galilaeus. The coefficient of determination values ranged between 0.954 and 0.972 in all three species, which showed a high degree of positive correlation between the L and W of all the fish. The monthly mean condition factor (K) estimated for each species ranged from 4.23 to 5.39 for O. niloticus, 4.21 to 5.32 for S. galilaeus, and 2.29 to 5.20 for C. zillii. The high condition factors (K) recorded in this study indicate that the fish stock is in excellent health, benefiting from good food availability, favorable environmental conditions, and low-stress levels. These findings suggest that the habitat provides optimal resources for growth and survival, contributing to the overall well-being of the fish.