Fatty acid profile of pebbly fish, Alestes baremoze (Joannis, 1835) from Lake Albert, Uganda: Implications for its feed requirements

The objective of this study was to establish the fatty acid profile of Alestes baremoze, with a view of establishing its dietary fatty acid requirements. Fish samples from Lake Albert were categorized into four classes according to fork lengths (1–10 cm, 11–20 cm, 21–30 cm, and 31–40 cm), with each class comprising of six fish. In addition, eggs were collected from six sexually mature females. A total of 35 fatty acids were identified and categorized into saturated fatty acids (SFAs), monounsaturated acids (MUFAs), and polyunsaturated fatty acids (PUFAs). SFAs accounted for 5.07% to 37.05%, MUFAs and PUFAs constituted 20.65% to 53.78%, and 10.34% to 66.10% respectively, of total fatty acids in all studied fish size classes. The results from this study indicated that fatty acid composition in A. baremoze varied significantly with size classes. The findings may provide guidance on the fatty acid inclusions for diets formulated for this fish under culture conditions

Prospects and Potential of the African Lungfish (Protopterus spp): Results from a Field Survey in Uganda

Culture of resilient species to drought and stressed water quality conditions may be a significant part of the future of African aquaculture. Air breathing fishes potentially have a role in low-management culture systems because dissolved oxygen is not a limiting factor. The African lungfish (Protopterus spp) is advantageous because it is an indigenous fish with good quality flesh, an air-breather and a biocontrol agent against schistosome vector snails. Little is known about indigenous practices of culture, harvest, and marketing of Protopterus spp from farm ponds and water bodies. This study assessed the status and potential of lungfish aquaculture in Uganda in seven districts in Kampala, Wakiso, Kumi, Busia, Soroti, Pallisa and Jinja. Semi-structured interviews were conducted with key stakeholders; fish farmers, fisher folk communities, Fisheries officers, scientists, fish traders, and consumers. Socio-economic conditions (prices, demand, and public perceptions) that shape the culture of African Lungfish were also assessed. African lungfish wild stocks in Uganda are continuously being reduced while no clear or sustainable mitigation measures/policies are being addressed to replenish the plummeted stocks. Lungfish is highly valued in major tribes of eastern of Uganda but gradually accepted in the central region. Majority of lungfish is consumed fresh but smoked products are also preferred. Its food and‚ medicinal‚ value is gradually substituting Tilapia and Nile perch markets, among the rural and densely populated communities. Cultural (traditional and religious) beliefs are main factors that continue to deter some consumers from eating Lungfish. However, preliminary findings in thisKeywords: Fisheries Economics, Fish & Aquaculture Sectors' Development, The Economics of Aquaculture Production and Profitability Part IIIKeywords: Fisheries Economics, Fish & Aquaculture Sectors' Development, The Economics of Aquaculture Production and Profitability Part II

Associations between red blood cell variants and malaria among children and adults from three areas of Uganda: a prospective cohort study.

BACKGROUND: Multiple red blood cell (RBC) variants appear to offer protection against the most severe forms of Plasmodium falciparum malaria. Associations between these variants and uncomplicated malaria are less clear. METHODS: Data from a longitudinal cohort study conducted in 3 sub-counties in Uganda was used to quantify associations between three red blood cell variants Hb [AA, AS, S (rs334)], alpha thalassaemia 3.7 kb deletion, and glucose-6-phosphate dehydrogenase deficiency A-(G6PD 202A genotype) and malaria incidence, parasite prevalence, parasite density (a measure of anti-parasite immunity) and body temperature adjusted for parasite density (a measure of anti-disease immunity). All analyses were adjusted for age, average household entomological inoculation rate, and study site. Results for all variants were compared to those for wild type genotypes. RESULTS: In children, HbAS was associated, compared to wild type, with a lower incidence of malaria (IRR = 0.78, 95% CI 0.66-0.92, p = 0.003), lower parasite density upon infection (PR = 0.66, 95% CI 0.51-0.85, p = 0.001), and lower body temperature for any given parasite density (- 0.13 ℃, 95% CI - 0.21, - 0.05, p = 0.002). In children, HbSS was associated with a lower incidence of malaria (IRR = 0.17, 95% CI 0.04-0.71, p = 0.02) and lower parasite density upon infection (PR = 0.31, 95% CI 0.18-0.54, p < 0.001). α-/αα thalassaemia, was associated with higher parasite prevalence in both children and adults (RR = 1.23, 95% CI 1.06-1.43, p = 0.008 and RR = 1.52, 95% CI 1.04-2.23, p = 0.03, respectively). G6PD deficiency was associated with lower body temperature for any given parasite density only among male hemizygote children (- 0.19 ℃, 95% CI - 0.31, - 0.06, p = 0.003). CONCLUSION: RBC variants were associated with non-severe malaria outcomes. Elucidation of the mechanisms by which they confer protection will improve understanding of genetic protection against malaria

Increasing Farmers’ Access to Aquaculture Extension Services: Lessons from Central and Northern Uganda

This paper focuses on examining the modalities of extension service provision, and determining feasible approaches for increasing accessibility among fish farmers in Uganda. The paper draws on a cross-sectional study involving fish farming households and extension workers to determine access to extension services for improved farming practices. Quantitative data were collected from 246 households using a semi-structured questionnaire. Qualitative data were generated from Key Informant interviews with selected extension workers, officials in charge of extension planning District Fisheries Officers and Fish Farmer Group leaders. Focus Group Discussions were also conducted with fish farmers. The results indicated a significant association between socioeconomic characteristics of fish farmers and access to extension services. Size of land owned, income from pond fish and membership to fish-farmer groups were the significant factors (P&lt;0.05). All the respondents reported pressing needs which required extension intervention. The respondents expressed the need to form effective farmer groups for the purpose of sharing knowledge, arriving at mutual agreement on scheduling extension activities and providing feedback to the extension workers. Specifically for the northern region, there is a need for the Fisheries Extension Officer to identify and respond to the extension needs of fish farmers through various means including ICTs. Identifying solutions to social, technical and institutional constraints in extension can increase access to services through constructive social interactions between farmers and extension agents. The article provides important lessons for practice and policy, and proposes a farmer-centred model, capable of facilitating increased access to aquaculture extension services in Uganda

Morphology and functional ontogeny of the digestive tract of Barbus altianalis larvae

The ontogenetic development of digestive structures in Ripon barbel (Barbus altianalis) larvae was investigated using standard histological and histochemical procedures from hatching up to 60 days after hatching (DAH). The study was conducted to determine the best period of exogenous feeding and the stage when the digestive tract is able to digest processed microdiets. Results indicated that at hatching, the digestive tract, mouth and anus were closed. The opening of the mouth and anus were observed 3–4 DAH, whereas complete separation of the entire gut was observed on 5 DAH. Exogenous feeding started 5–6 DAH, but complete yolk exhaustion occurred 7–8 DAH, indicating a period of mixed feeding. Mucosal epithelial folds were first noted 3 DAH in the anterior intestine and became profound with some goblet cells (mucous cells) by 6 DAH. At 7 DAH the mucous cells had started secreting both neutral and acid glycoconjugates. The first intestinal single loop occurred at 28–30 DAH and a double loop at 45–50 DAH. Each coiling was proceeded by larval weight increase. By 7 DAH the buccopharyngeal cavity was lined by a layer of squamous epithelial cells with scattered goblet cells and tastebuds that became numerous by 15 DAH. At hatching, the liver and the pancreas were undifferentiated, but on 3 DAH the hepatocytes and zymogen granules of the pancreas became clear. By 7 DAH both organs enlarged, making extensions into the posterior. Intestines coiling at 28–30 DAH coincided with the beginning of external dressing of the scales, a period when B. altianalis started transforming into a juvenile. By 7–8 DAH the digestive structure showed all the necessary digestive features that could enable the larvae to digest any compound diet suggesting that it may be feasible to substitute or offer a complete microdiet during larvae nursing with reduced larval mortality.Keywords: digestive structures, exogenous feeding, microdiet, mucins, ontogenetic development, Ripon barbe

Hydrodynamics of Lake Victoria: Vertically integrated flow models in COMSOL Multiphysics.

Lake Victoria is the largest tropical lake in the world and is very important for environment andeconomy in East Africa. The hydrodynamic processes in the shallow (40-80 m deep) watersystem are unique due to its location at the equator which makes Coriolis effects noticeable alsofor vertical transport. The limited river inflow, and the large surface area compared to its volumemake Lake Victoria vulnerable to climate changes. A model of the circulation patterns, mixing,dispersion and stratification will be necessary to devise strategies for management of the naturalresources. The goal of this project is to improved water quality of Lake Victoria.COMSOL Multiphysics® software supports models for the different processes to be included,and we are developing interfaces used by the geo-hydrodynamical community, such as theDigital Elevation Map (DEM) file format. However, much data remains to collect and coordinatebefore the goal is reached. It turns out that modern depth soundings covering the whole lake maynot be available so scarce and old data have to be used initially. To assess the data collected, amodeling approach can be employed. Data for river in- and outflow as well as evaporation andrainfall have been collected for many years and can be correlated with data series for lake waterlevels in the simulation model.As a first step we have built a vertically integrated St. Venant shallow water model to look at theeffects of bottom topography on large-scale flow patterns and the water level variation. TheCOMSOL® coefficient form PDE represents streamline artificial viscosity, Coriolis forces, andbottom friction, with boundary conditions representing river in- and outflow. The topographymodel must have continuous gradients, and a combination of Kriging with Delaunay triangulationis used to produce the surface model. Results of the long-time simulations will be presented aswell as numerical experiments with other approximate flow models to represent the moving watersurface.QC 20231101</p

Bathymetry Development and Flow Analyses Using Two-Dimensional Numerical Modeling Approach for Lake Victoria

This study explored two-dimensional (2D) numerical hydrodynamic model simulations of Lake Victoria. Several methods were developed in Matlab to build the lake topography. Old depth soundings taken in smaller parts of the lake were combined with more recent extensive data to produce a smooth topographical model. The lake free surface numerical model in the COMSOL Multiphysics (CM) software was implemented using bathymetry and vertically integrated 2D shallow water equations. Validated by measurements of mean lake water level, the model predicted very low mean flow speeds and was thus close to being linear and time invariant, allowing long-time simulations with low-pass filtered inflow data. An outflow boundary condition allowed an accurate simulation to achieve the lake’s steady state level. The numerical accuracy of the linear measurement of lake water level was excellent.QC 20191106. QC 20200129PhD projec

Hydrodynamics of Lake Victoria: Vertically integrated flow models in COMSOL Multiphysics.

Lake Victoria is the largest tropical lake in the world and is very important for environment andeconomy in East Africa. The hydrodynamic processes in the shallow (40-80 m deep) watersystem are unique due to its location at the equator which makes Coriolis effects noticeable alsofor vertical transport. The limited river inflow, and the large surface area compared to its volumemake Lake Victoria vulnerable to climate changes. A model of the circulation patterns, mixing,dispersion and stratification will be necessary to devise strategies for management of the naturalresources. The goal of this project is to improved water quality of Lake Victoria.COMSOL Multiphysics® software supports models for the different processes to be included,and we are developing interfaces used by the geo-hydrodynamical community, such as theDigital Elevation Map (DEM) file format. However, much data remains to collect and coordinatebefore the goal is reached. It turns out that modern depth soundings covering the whole lake maynot be available so scarce and old data have to be used initially. To assess the data collected, amodeling approach can be employed. Data for river in- and outflow as well as evaporation andrainfall have been collected for many years and can be correlated with data series for lake waterlevels in the simulation model.As a first step we have built a vertically integrated St. Venant shallow water model to look at theeffects of bottom topography on large-scale flow patterns and the water level variation. TheCOMSOL® coefficient form PDE represents streamline artificial viscosity, Coriolis forces, andbottom friction, with boundary conditions representing river in- and outflow. The topographymodel must have continuous gradients, and a combination of Kriging with Delaunay triangulationis used to produce the surface model. Results of the long-time simulations will be presented aswell as numerical experiments with other approximate flow models to represent the moving watersurface.QC 20231101</p

Molecular Characterization and Antibiotic Susceptibility of Edwardsiella tarda isolated from Farmed Nile Tilapia and African Catfish from Wakiso, Uganda

This study was conducted to isolate and characterize Edwardsiella tarda (E. tarda) and assess its antimicrobial susceptibility. The bacterium was isolated in Wakiso District, Uganda, from symptomatic and asymptomatic Nile tilapia and African catfish raised in earthen ponds, tanks and cages between September 2016 and February 2017. The bacterium was then identified using conventional biochemical tests and API 20E test kits and characterized by sequencing 16S rRNA gene. The antibiotic susceptibility of 16 drugs was established using the Kirby BeurDisc diffusion method. Eight E. tarda isolates were identified using conventional biochemical tests but only one isolate was confirmed to be E. tarda by PCR. Phylogenetic analysis indicated a distant relationship with other 16S rRNA gene sequences retrieved from the GenBank. Six virulence genes (CitC, muk, gadB, katB, esaV, and fimA) that enhance bacterial survival and pathogenesis in the host were detected. The isolate registered low levels of antibiotic resistance as it was resistant only to Oxacillin, Vancomycin and Penicillin, to which it is intrinsically resistant. This implies low antibiotic usage in aquaculture in the area. Despite its low occurrence, presence of virulent genes in E. tarda indicates its potential to affect fish and human health