Oyugi D.O.,Jaramogi Oginga Odinga University of Science and Technology |
Mavuti K.M.,University of Nairobi |
Aloo P.A.,Karatina University |
Ojuok J.E.,Kenya Marine and Fisheries Research Institute |
Britton J.R.,Bournemouth University
Hydrobiologia | Year: 2014
Habitat suitability indices indicate how fish species respond to different habitat types. We assessed effects of habitat characteristics on fish distribution in an equatorial lake, Lake Naivasha, Kenya, where habitats vary according to substrate, depth and turbidity. Using monthly data between 2008 and 2010 using multi-mesh gill nets, catch per unit effort was used as a relative abundance measure to identify how habitat variables drive fish distribution. The focus was on commercial fishes: two introduced species (Cyprinus carpio and Micropterus salmoides) and two naturalised species (Oreochromis leucostictus and Tilapia zillii). Analyses revealed distinct preferences for different habitat variables by all commercial species except for C. carpio. For example, O. leucostictus preferred shallow waters with silt-clay substrates whilst M. salmoides preferred deeper waters with sandy/rocky substrates. Conversely, C. carpio showed no specialised habitat requirements. Niche overlaps were significantly lower between O. leucostictus and its respective sympatric species than between other species, a likely result of its territorial behaviour. The continued environmental degradation of Lake Naivasha may imperil the preferred habitats of the niche restricted M. salmoides, O. leucostictus and T. zillii. By contrast, the ubiquity of C. carpio may facilitate their invasion, and consequently sustain their dominance in the lake's commercial fishery. © 2014 The Author(s).
PubMed | University of Nairobi, Karatina University and Mpala Research Center
Type: | Journal: Ecological applications : a publication of the Ecological Society of America | Year: 2016
In many savanna ecosystems worldwide, livestock share the landscape and its resources with wildlife. The nature of interactions between livestock and wildlife is a subject of considerable interest and speculation, yet little controlled experimental research has been carried out. Since 1995, we have been manipulating the presence and absence of cattle and large mammalian herbivore wildlife in a Kenyan savanna in order to better understand how different herbivore guilds influence space use by specific wildlife species. Using dung counts as a relative assay of herbivore use of the different experimental plots, we found that cattle had a range of effects, mostly negative, on common mesoherbivore species, including both grazers and mixed feeders, but did not have significant effects on megaherbivores. The effect of cattle on most of the mesoherbivore species was contingent on both the presence of megaherbivores and rainfall. In the absence of megaherbivores, wild mesoherbivore dung density was 36% lower in plots that they shared with cattle than in plots they used exclusively, whereas in the presence of megaherbivores, wild mesoherbivore dung density was only 9% lower in plots shared with cattle than plots used exclusively. Cattle appeared to have a positive effect on habitat use by zebra (a grazer) and steinbuck (a browser) during wetter periods of the year but a negative effect during drier periods. Plots to which cattle had access had lower grass and forb cover than plots from which they were excluded, while plots to which megaherbivores had access had more grass cover but less forb cover. Grass cover was positively correlated with zebra and oryx dung density while forb cover was positively correlated with eland dung density. Overall these results suggest that interactions between livestock and wildlife are contingent on rainfall and herbivore assemblage and represent a more richly nuanced set of interactions than the longstanding assertion that cattle simply compete with (grazing) wildlife. Specifically, rainfall and megaherbivores seemed to moderate the negative effects of cattle on some mesoherbivore species. Even if cattle tend to reduce wildlife use of the landscape, managing simultaneously for livestock production (at moderate levels) and biodiversity conservation is possible. This article is protected by copyright. All rights reserved.
Kebwaro J.M.,Karatina University |
He C.H.,Xi'an University of Science and Technology |
Zhao Y.L.,Xi'an University of Science and Technology
Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms | Year: 2016
Radiative capture reactions are of interest in shielding design and other fundamental research. In this study the reproducibility of (n,γ) reactions in Pb when cross-section data from different ENDF/B releases are used in the Monte-Carlo code, MCNP, was investigated. Pb was selected for this study because it is widely used in shielding applications where capture reactions are likely to occur. Four different neutron spectra were declared as source in the MCNP model which consisted of a simple spherical geometry. The gamma ray spectra due to the capture reactions were recorded at 10 cm from the center of the sphere. The results reveal that the gamma ray spectrum produced by ENDF/B-V is in reasonable agreement with that produced when ENDF/B-VI.6 is used. However the spectrum produced by ENDF/B-VII does not reveal any primary gamma rays in the higher energy region (E > 3 MeV). It is further observed that the intensities of the capture gamma rays produced when various releases are used differ by a some margin showing that the results are not reproducible. The generated spectra also vary with the spectrum of the source neutrons. The discrepancies observed among various ENDF/B releases could raise concerns to end users and need to be addressed properly during benchmarking calculations before the next release. The evaluation from ENDF to ACE format that is supplied with MCNP should also be examined because errors might have arisen during the evaluation. © 2016 Elsevier B.V. All rights reserved.
Ngemu E.K.,University of Eldoret |
Khayeka-Wandabwa C.,Jomo Kenyatta University of Agriculture and Technology |
Kweka E.J.,Tropical Pesticides Research Institute |
Choge J.K.,University of Eastern Africa, Baraton |
And 2 more authors.
BMC Research Notes | Year: 2014
Background: Ensuring that no baby is born with HIV is an essential step towards achieving an AIDS-free generation. To achieve this, strategies that decouple links between childbirth and HIV transmission are necessary. Traditional forms of prevention of mother-to-child transmission of HIV (PMTCT), has been recommended. Recognizing the importance and challenges of combination of methods to achieve rapid PMTCT, the World Health Organization (WHO) recommended option B Highly Active Antiretroviral Therapy (HAART) for all HIV-positive pregnant women. This study aimed to evaluate the effectiveness of the HAART in PMTCT. A cohort of HIV-infected pregnant women in Kenya were obtained from the DREAM Center, Nairobi. The study participants underwent adherence counselling and Option B of HAART [Nevirapine(NVP) + Lamivudine + Zidovudine] at the fourth week of gestation followed by an intravenous NVP administration intrapartum and postpartum NVP syrup to the respective infants for six weeks. Absolute pre-HAART and post-HAART CD4 counts and viral loads counts were determined. Comparison of the CD4 counts and viral loads before and after administration of HAART were done using Wilcoxon's Matched Pairs Signed-Ranks Test. Findings. The mean absolute CD4 cell counts in mothers after administration of HAART was significantly higher (Z = 15.664, p < 0.001) than before the administration of HAART). Also the viral load of the mothers significantly (Z = 11.324, p < 0.001) reduced following HAART treatment. Following the HAART administration in mothers, up to 90% of children were confirmed to be HIV negative. Conclusion: Administration of HAART to mothers and children demonstrated an effective mechanism of PMTCT. However, other aspects of HAART such as adherence, costs, mothers behaviour during HAART, and the child feeding programme during the therapy should further be evaluated and ascertained how they can affect the overall efficacy of option B HAART in PMTCT. © 2014 Ngemu et al.; licensee BioMed Central Ltd.
Kimanzi J.K.,University of Eldoret |
Sanderson R.A.,Northumbria University |
Rushton S.P.,Northumbria University |
Mugo M.J.,Karatina University
ORYX | Year: 2015
Poaching with snares has been identified as the main cause of decline of the endemic roan antelope Hippotragus equinus langheldi in Ruma National Park, Kenya, from > 200 in 1979 to 37 in 2009. However, the spatial snaring patterns in the Park are not clearly understood. The focus of our study was to map the spatial distribution of snares in the Park and to identify the factors influencing this distribution, to develop effective methods of wildlife protection. Using data collected from 56 sample plots during 2006-2008, coupled with geographical information system techniques, we investigated the association between the occurrence of snares and the distribution of geographical features (slope, elevation), infrastructure (roads, fences), essential resources for wildlife (water, salt licks, forage), roan locations and wildlife density. Ripley's L function for assessing complete spatial randomness indicated that snares occurred in clumps (hotspots) up to 4 km apart. Negative binomial regression indicated that these hotspots occurred (1) near water resources, salt licks and the Park boundary, (2) far from roan locations and Park roads, (3) in areas with low gradients and low wildlife density, and (4) in areas with burned vegetation. We recommend concentrating routine security patrol efforts and resources on snare hotspots to reduce snaring and to protect the roan antelope and other threatened wildlife. Copyright © Fauna & Flora International 2014.
PubMed | Karatina University, University of Eldoret, Moi University, Kenya Marine and Fisheries Research Institute and 2 more.
Type: Journal Article | Journal: Environmental monitoring and assessment | Year: 2016
Polychlorinated biphenyls (PCBs) are classified as persistent organic pollutants (POPs) regulated by the Stockholm Convention (2001). Although their production and use was stopped almost three decades ago, PCBs are environmental persistent, toxic, and bioaccumulate in biota. We assessed the levels of 7 PCB congeners (IUPAC nos. 28, 52, 101, 118, 138, 153, and 180) in sediment and fish (Oreochromis niloticus, Lates niloticus, and Rastrineobola argentea) and evaluated the potential of cestode fish endoparasite (Monobothrioides sp., Proteocephalaus sp., and Ligula intestinalis) as biomonitors of PCBs in Lake Victoria, Kenya. The median concentration of 7PCBs in sediments and fish were 2.2-96.3g/kg dw and 300-3,000g/kg lw, respectively. At all the sampling sites, CB138, CB153, and CB180 were the dominant PCB congeners in sediment and fish samples. Compared to the muscle of the piscine host, Proteocephalaus sp. (infecting L. niloticus) biomagnified PCBs 6-14 while Monobothrioides sp. (infecting O. niloticus) biomagnified PCBs 4-8. Meanwhile, L. intestinalis (infecting R. argentea) biomagnified PCBs 8-16 compared to the muscle of unparasitized fish. We demonstrate the occurrence of moderate to high levels of PCB in sediments and fish in Lake Victoria. We also provide evidence that fish parasites bioaccumulate higher levels of PCBs than their piscine hosts and therefore provide a promising biomonitor of PCBs. We urge further a long-term study to validate the use of the above cestode fish parasites as biomonitoring tools for PCBs.
PubMed | Kenyatta University, Karatina University and University of Eldoret
Type: Journal Article | Journal: Fish & shellfish immunology | Year: 2015
We investigated effects of dietary administration of stinging nettle (Urtica dioica) on growth performance, biochemical, hematological and immunological parameters in juvenile and adult Victoria Labeo (Labeo victorianus) against Aeromonas hydrophila. Fish were divided into 4 groups and fed for 4 and 16 weeks with 0%, 1%, 2% and 5% of U.dioica incorporated into the diet. Use of U.dioica in the diet resulted in improved biochemical, hematological and immunological parameters. Among the biochemical parameters; plasma cortisol, glucose, triglyceride and cholesterol decreased while total protein and albumin in fish increased with increasing dietary inclusion of U.dioica. Among the haematology parameters: red blood cell (RBC), white blood cell (WBC) counts, haematocrit (Htc), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and netrophiles increased with increasing dietary inclusion levels of U.dioica, some depending on the fish age. Serum immunoglobulins, lysozyme activity and respiratory burst were the main immunological parameters in the adult and juvenile L.victorianus measured and they all increased with increasing herbal inclusion of U.dioica in the diet. Dietary incorporation of U.dioica at 5% showed significantly higher relative percentage survival (up to 95%) against A.hydrophila. The current results demonstrate that using U.dioica can stimulate fish immunity and make L.victorianus more resistant to bacterial infection (A.hydrophila).
Ngugi C.C.,University of Nairobi |
Oyoo-Okoth E.,Karatina University |
Muchiri M.,Karatina University
Aquaculture Research | Year: 2016
Essential oils (EOs) are used in the food industry because of their biological activity. We evaluated the effects of administration of essential oil (EO) extracted from bitter lemon (Citrus limon) fruit peels on the growth performance, biochemical, haemato-immunological parameters and possible disease resistance in fingerlings (4 weeks old) Labeo victorianus challenged with Aeromonas hydrophila. Fish were divided into five groups and fed diets supplemented with C. limon fruit peels EO extract at 1%, 2%, 5% and 8% [as fed basis] and treatment compared with control group fed diet without C. limon fruit peels EO extract. The experiment was executed in triplicate. Concentration of plasma cortisol, glucose, triglyceride and cholesterol decreased while that of total protein and albumin increased as dietary inclusion of the EO extract of C. limon fruit peels was increased from 2% to 5%. Meanwhile haemato-immunological parameters including red blood cell (RBC), white blood cell (WBC) counts, haematocrit (Htc), mean cell haemoglobin (MCH), mean cell haemoglobin concentration (MCHC) and neutrophiles increased with increasing dietary inclusion from 1% to 5% inclusion of C. limon fruit peels EO extract. Serum immunoglobulins, lysozyme activity and respiratory burst increased with increasing dietary levels up to 5% inclusion of EO extract of C. limon fruit peels. We demonstrate that formulation of feeds by incorporating upto 5% the EO extract from C. limon fruit peels significantly improved biochemical, haematological and immunological response in juvenile fish resulting to lower mortality than the untreated groups and appear to be effective antibacterial against A. hydrophila. © 2016 John Wiley & Sons Ltd.
Kamiri H.,Karatina University |
Kreye C.,University of Bonn |
Becker M.,University of Bonn
Wetlands Ecology and Management | Year: 2013
Agricultural land use changes differentially affect soil fertility and crop production potential of wetlands. We studied East African wetlands with contrasting hydro-geological characteristics (high- and lowland floodplains and valley swamps). Land uses ranged from no use and grazing over crop production in flooded and drained fields to abandonment. We classified the dynamics of wetlands' conversion into agricultural sites and assessed selected soil fertility attributes associated with land use changes, and their effect on the crop production potential in aerobic and anaerobic soils. A conversion of pristine wetlands, differing in soil physical and chemical attributes, into sites of production tended to negatively affect soil total C and N. Effects were stronger with soil drainage and in the coarse-textured soils of the lowland floodplain and the mid-hill valleys. Mineral P application in drained valleys significantly increased available soil P. Crop response followed these patterns with usually higher biomass accumulation and nutrient uptake in flooded than aerobic soils. Wetlands of fine soil texture in the highlands appeared more resilient than coarse-textured soils, particularly when drained. Enhanced crop performance in flooded soils indicates the possibility for partial recovery of the production potential and the rehabilitation of some wetlands. © 2013 Springer Science+Business Media Dordrecht.
Gichunge C.,Karatina University |
Harris N.,Griffith University |
Tubei S.,Griffith University |
Somerset S.,Australian Catholic University |
Lee P.,Griffith University
Journal of Hunger and Environmental Nutrition | Year: 2015
The objective of this cross-sectional study was to assess the interaction of food insecurity, social support, and vegetable intake among resettled Burundian, Congolese, and Rwandan African refugees in Australia. A total of 71 household food preparers were recruited through purposive sampling. Eighteen percent of the participants experienced food insecurity. Participants with low education and no social support were 5 and 4 times more likely to be food insecure, respectively. There were no significant differences in vegetable intake. Results indicate that food insecurity is more prevalent among postresettlement African refugees compared to the general Australian population and is associated with social support and education. Strategies to enhance education and social support networks for resettled African refugees may work toward alleviating food insecurity among this group. Copyright © Taylor & Francis Group, LLC.