Outa N.O.,Maseno University |
Yongo E.,University of Eldoret |
Keyombe J.A.,Kenya Marine and Fisheries Research Institute
Lakes and Reservoirs: Research and Management | Year: 2017
A total of 289 fish were analysed in this study, with Caradina nilotica (44%) being the dominant food item in their diet, while tilapia (8%) contributed the least. Haplochromines, unidentified fish prey and juvenile Nile perch also were observed. An ontogenic shift was observed, with C. nilotica contributing highest (61.1%) of the diet of fingerlings, but decreasing to 21% in the diet of adults. Nile perch contributed 35.7% of the diet in the adults and 8.1% in the fingerlings. This study indicates Nile perch is a predatory fish, feeding mainly on C. nilotica, haplochromines, tilapia, Nile perch and other fish materials. © 2017 John Wiley & Sons Australia, Ltd
Downing T.A.,University of Eldoret |
Imo M.,University of Eldoret |
Kimanzi J.,University of Eldoret |
Otinga A.N.,University of Eldoret
Catena | Year: 2017
Tropical alpine ecosystems serve vital roles in the areas of hydrology, biodiversity and carbon storage, due to their unique set of climatic and topographic conditions. These ecosystems are particularly vulnerable to climate change and anthropogenic influence as they exist in a fragile balance. Mount Kenya is an example of such a tropical alpine environment, and in 2012 a large fire burned through the upper southwestern slopes of the mountain. The fire burned at the transition zone between the moorland and the forest at an elevation of 3300–4000 m, and covered almost 100 km2. The impacts of this fire on soil properties are investigated three years after the fire. The severity from the time of the fire was determined using a satellite derived index known as dNBR (difference Normalized Burn Ratio). This was used to stratify the fire scar into 3 classes: low, moderate, and high severity areas. Soil samples were collected from the top 10 cm layer (O-horizon) in each of these 3 severity classes and from unburnt areas outside the fire scar, and analyzed in the laboratory for physical and chemical properties. The results mostly showed no difference in soil properties between the three severity classes and unburnt areas. Only cation exchange capacity (CEC) and bulk density were found to be significantly different between the severity classes (p < 0.001 and p = 0.003 respectively), with high severity areas having lower bulk density and higher CEC as compared to unburnt areas. When other explanatory variables were taken into consideration, only CEC remained significantly different according to severity rating. CEC increased from 40.13 cmolc kg− 1 outside the fire to 65.91 cmolc kg− 1 in the high severity areas. The increase in CEC can be explained either by an increase in organic matter, as partially burnt material gradually incorporated into the soil, or by a change in the quality of the organic matter. Thus the impact of fire on soil properties in the tropical alpine moorland of Mount Kenya appears to be small, at least after 3 years. © 2016 Elsevier B.V.
Raburu P.O.,University of Eldoret |
Masese F.O.,University of Eldoret |
Tonderski K.S.,Linköping University
Environmental Monitoring and Assessment | Year: 2017
Wastewater discharge from sugarcane processing is a significant pollutant of tropical aquatic ecosystems. For most developing countries, monitoring of the level of pollutants is done mostly through chemical analysis, but this does not reflect potential impacts on aquatic assemblages. In addition, laboratory facilities for accurate concentration measurements are often not available for regular monitoring programs. In this study, we investigated the use of benthic macroinvertebrates for biological monitoring in western Kenya. Benthic macroinvertebrates were sampled in stabilization ponds treating wastewater from sugarcane- and molasses-based processing plants to assess their composition and abundance in relation to different concentrations of chemical variables. Optimum concentrations and tolerance values were identified for various taxa, and a biotic index was developed that combined tolerance values (ranked between 0 and 10) for the various macroinvertebrate taxa. A succession in composition and distribution of macroinvertebrate taxa was observed from the inlet to the outlet of the pond systems. Diptera dominated in the first ponds that had high concentrations of chemical oxygen demand (COD), biological oxygen demand (BOD5), and nutrients, while intolerant Ephemeroptera, Plecoptera, and Trichoptera (EPT) appeared as the concentrations dropped in subsequent ponds. The effluent quality was classified as “good,” “fair,” and “poor,” corresponding with biotic index value ranges 0–3.50, 3.51–6.50, and 6.51–10, respectively. During validation, the index grouped sites with respect to levels of measured environmental variables. The study revealed that the developed biotic index would help in monitoring the quality of sugarcane processing and molasses effluents before release into recipient aquatic ecosystems, replacing the need for costly chemical analyses. © 2017, Springer International Publishing Switzerland.
Yongo E.,University of Eldoret |
Outa N.,Egerton University
Lakes and Reservoirs: Research and Management | Year: 2016
The Nile tilapia (Oreochromis niloticus) was introduced into Lake Victoria in the early 1950s and 1960s and has since become the dominant tilapiine in the lake. This study investigated the growth and population parameters of O. niloticus in Lake Victoria on the basis of length–frequency data collected during the period June 2014 and June 2015. The asymptotic length (L∞) had a mean (±SE) value of 46.24 ± 0.04 cm TL, growth curvature (K) of 0.69 ± 0.25 year−1, total mortality (Z) of 2.18 ± 0.80 year−1, a natural mortality (M) of 1.14 ± 0.28 year−1, a fishing mortality (F) of 1.05 ± 0.53 year−1, an exploitation rate (E) of 0.46 ± 0.08, a growth performance index (∅) of 3.14 ± 0.17 and a length at first capture (LC50) of 20.31 ± 0.40 cm TL. Comparing the results of this study with previous studies indicates the parameters K, Z and M have increased, whereas ∅, F, E and LC 50 have decreased. Changes in these parameters could be attributed to the existing high fishing capacity, and changing lake conditions. Thus, management measures should include continued restriction on illegal fishing methods and gears, such as the use of undersized gillnets (<5 in. mesh size) and beach seines. More attention also should be directed to the implementation of measures to control pollution of the lake from its various sources. © 2017 John Wiley & Sons Australia, Ltd
Wambu E.W.,Jaramogi Oginga Odinga University of Science and Technology |
Agong S.G.,Jaramogi Oginga Odinga University of Science and Technology |
Anyango B.,Jaramogi Oginga Odinga University of Science and Technology |
Akuno W.,Jaramogi Oginga Odinga University of Science and Technology |
Akenga T.,University of Eldoret
BMC Public Health | Year: 2014
Background: Only a few studies to evaluate groundwater fluoride in Eastern Africa have been undertaken outside the volcanic belt of the Great Eastern Africa Rift Valley. The extent and impact of water fluoride outside these regions therefore remain unclear. The current study evaluated fluoride levels in household water sources in Bondo-Rarieda Area in the Kenyan part of the Lake Victoria Basin (LVB) and highlighted the risk posed by water fluoride to the resident communities. The results, it was anticipated, will contribute to in-depth understanding of the fluoride problem in the region. Methods. A total of 128 water samples were collected from different water sources from the entire study area and analyzed for fluoride content using ion-selective electrodes. Results: Lake Victoria was the main water source in the area but dams and open pans (39.5%), boreholes and shallow wells (23.5%), and streams (18.5%) were the principal water sources outside walking distances from the lake. The overall mean fluoride content of the water exceeded recommended limits for drinking water. The mean water fluoride was highest in Uyoma (1.39±0.84 ppm), Nyang'oma (1.00±0.59 ppm) and Asembo (0.92±0.46 ppm) and lowest in Maranda Division (0.69±0.42 ppm). Ponds (1.41±0.82 ppm), springs (1.25±0.43 ppm), dams and open pans (0.96±0.79 ppm), and streams (0.95±0.41 ppm) had highest fluoride levels but lake and river water did not have elevated fluoride levels. Groundwater fluoride decreased with increasing distance from the lake indicating that water fluoride may have hydro-geologically been translocated into the region from geochemical sources outside the area. Conclusions: Lake Victoria was the main water source for the residents of Bondo-Rarieda Area. Majority of in-land residents however used water from dams, open pans, boreholes, shallow wells, ponds and streams, which was generally saline and fluoridated. It was estimated that 36% of children living in this area, who consume water from ground sources from the area could be at the risk of dental fluorosis. © 2014 Wambu et al.; licensee BioMed Central Ltd.
Agency: European Commission | Branch: H2020 | Program: RIA | Phase: WATER-5c-2015 | Award Amount: 2.99M | Year: 2016
FLOWERED objective is to contribute to the development of a sustainable water management system in areas affected by fluoride (F) contamination in water, soils and food in the African Rift Valley countries (Ethiopia, Kenya, Tanzania), thus to improve living standards (environmental, health and food security) of its population. FLOWERED aims to study, test and implement innovative defluoridation technologies for drinking and irrigation water that will mainly operate at small village scale and to develop an integrated, sustainable and participative water and agriculture management at a cross-boundary catchment scale. On the basis of the complexity of the issue of water de-fluoridation, the proposed scientific approach in FLOWERED is based on a detailed knowledge of the geological and hydrogeological setting that controls contamination of water that constitute the prerequisite for the implementation of a sustainable water management and for the proposal of sustainable and suitable strategies for water sanitation and agricultural system. Innovative agricultural practices will be assessed, aiming to mitigate the impacts of F contamination of water and soil on productivity of selected food and forage crops and dairy cattle health and production. The development of an innovative and shared Geo-data system will support the integrated, sustainable and participative management system. FLOWERED, focusing on innovative technologies and practices and taking into account local experiences, will implement an integrated water and agriculture management system and will enable local communities to manage water resources, starting from using efficient defluoridation techniques and applying sustainable agricultural practices. The integrated approaches improve knowledge for EU partners, local researchers, farmers and decision makers. The Project through the involvement of SMEs will strengthen the development co-innovative demonstration processes as well as new market opportunities.
Njoroge R.W.,University of Eldoret |
Macharia B.N.,Moi University |
Sawe D.J.,Moi University |
Maiyoh G.K.,Moi University
Toxicology Reports | Year: 2015
The use of crude kerosene as a dietary supplement in boarding schools has been a common practice in east Africa and other countries for many years, with the belief of it reducing the sex drive (libido) at the pubertal stage. There is however no scientific basis for this belief. The present study aimed at using a rat animal model to investigate the effects of crude kerosene on serum testosterone levels, aggression and its possible toxic effects. Fifteen male albino rats of approximately similar age and average weights were put into three groups of five animals each; the control group (placebo), low kerosene dose (10. μl/day) group and high kerosene dose (300. μl/day) group. ELISA was used to determine the serum testosterone levels. During treatment, changes in aggression were observed and noted. Liver toxicity was determined using enzyme assays, total protein and albumin while renal toxicity was monitored using serum creatinine levels. A full hemogram was conducted to determine hematological effects. Various tissue biopsies were obtained and examined using histopathological techniques for evidence of toxicity. Contrary to the common belief, our findings showed an overall increase of serum testosterone levels of up to 66% in the low dose and 75% in the high dose groups, with an increasing trend by the end of the study. The high dose group showed significantly increased levels of white blood cells (WBC) (. p=. 0.036), red blood cells (RBC) (. p=. 0.025), hematocrit (HCT) (. p=. 0.03), red cell distribution width (. p=. 0.028) and platelets (. p=. 0.017). The histological results of the stomach indicated chronic gastritis. © 2014 The Authors.
Chibole O.K.,University of Eldoret
Ecohydrology and Hydrobiology | Year: 2013
To investigate the water quality status at catchment scale, the MIKE 11 modeling system (DHI) was used on the Sosiani, western Kenya. The river's catchment was delineated according to land-use practice into forested (Fz), agricultural (Az) and urban (Uz). Rainfallrunoff processes were modeled using NAM (DHI) and the hydrodynamic model was built using the MIKE 11 HD module. Water quality (WQ) modeling was limited to the oxygen cycle. Model calibration was done on the basis of available measured WQ data at Fz-Az; Az-Uz boundaries. Simulated data versus observed data show model efficiency of 0.70. The Uz contributes 75% of BOD flux in the catchment. © 2013 European Regional Centre for Ecohydrology of Polish Academy of Sciences.
Modelling hydrological processes, crop yields and NPS pollution in a small sub-tropical catchment in South Africa using ACRU-NPS [Modélisation des processus hydrologiques, du rendement des cultures et de la pollution azote-phosphore-sédiment dans un petit bassin versant subtropical d’Afrique du Sud utilisant ACRU-NPS]
Kollongei K.J.,University of KwaZulu - Natal |
Kollongei K.J.,University of Eldoret |
Lorentz S.A.,University of KwaZulu - Natal
Hydrological Sciences Journal | Year: 2015
The Agricultural Catchment Research Unit—Nitrates, Phosphorous and Sediments (ACRU-NPS) model, which simulates runoff, sediment and nutrient (NO3 and P) production in agricultural catchments, is used to evaluate the impact of farming practices and land-use changes on crop yields, water discharge, sediment and nutrient loads in the 41-km2 Mkabela catchment in the KwaZulu-Natal midlands, South Africa. The ACRU-NPS model was modified with the following objectives: (a) to develop and incorporate algorithms to simulate crop growth and NPS pollution dynamics in process zones and control features; (b) simulate sediment and nutrient production from land segments for various land uses; (c) model crop yield where crop growth is influenced by water and nitrogen stress; and (d) simulate sediment and nutrient fate at controls and buffers in the stream network. Five management practice scenarios were simulated and run with a series of fertilizer management applications. The resulting crop yields, water discharge, sediment and nutrient loadings were analysed. On average, doubling fertilizer application from base rates resulted in the highest sugarcane yield increase of 5 t/ha, zero fertilizer application resulted in the highest sugarcane yield reduction of 11 t/ha, while applying deficit irrigation, with base fertilizer application rates retained, resulted in 16 t/ha sugarcane yield increase. Flood attenuation and retention capacities for the total non-point source (NPS) pollutants for the period 2006–2012 were also investigated in the study area. © 2015 IAHS.
Masese F.O.,University of Eldoret |
Omukoto J.O.,Kenya Marine and Fisheries Research Institute |
Nyakeya K.,Kenya Marine and Fisheries Research Institute
Ecohydrology and Hydrobiology | Year: 2013
Degradation of aquatic ecosystems in the Lake Victoria basin (LVB) and the rest of East Africa has elicited concern because of its bearing on social and economic development. Rapid population growth, industrialization and its associated urbanization, agricultural intensification and habitat loss have increased pressure on the integrity of water resources. Costs associated with traditional approaches to monitoring water quality have become prohibitive while not giving reliable early warning signals on resource condition to aquatic resource managers. The purpose of this paper is to explore approaches to developing macroinvertebrate- and fish-based biomonitoring tools in the LVB and East Africa and the challenges they face through a review of studies that have been carried out in the region. The hypothesis is that aquatic biota in the LVB provides cost-effective and integrative measures of the physical and chemical habitat conditions thus necessitating their use in assessment and monitoring of water resources. In the LVB macroinvertebrate and fish based indices of biotic integrity (IBIs) have demonstrated their utility in identifying sources of impairment, determining the extent of impacts and stand to give natural resource managers a scientifically defensible rationale for developing guidelines for conservation and management. Despite this significant step, however, adoption and use of indices as part of regular monitoring programs are yet to be realized. We recommend for the advancement and adoption of biological criteria as an integrated approach to monitoring human-induced stress in riverine ecosystems of the East Africa region. © 2013 European Regional Centre for Ecohydrology of Polish Academy of Sciences.