Browsing by Author "Oyoo-Okoth, Elijah"

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    Contribution of Soil, Water and Food Consumption To Metal Exposure of Children From Geological Enriched Environments in The Coastal Zone of Lake Victoria, Kenya
    (International Journal of Hygiene and Environmental Health, 2012) Oyoo-Okoth, Elijah; Admiraal, Wim; Osona, Odipo; Manguya-Lusega, David; Ngure, Veronica; Kraak, Michiel H. S.; Chepkirui-Boit, Victoria; Makwali, Judith
    Geologically enriched environments may contain high concentrations of some metals. In areas where industrial exposures remain super cial, children may be exposed to these geological metals through soil, drinking water and consumption of food locally grown. The aim of this study was to assess the contribution of soil, water and food consumption to cadmium (Cd), chromium (Cr), copper (Cu), zinc (Zn), cobalt (Co) and titanium (Ti) body burden of children in the geologically metal rich coastal zone of Lake Victoria, Kenya. We evaluated the relationship between the metal body burden of children by analyzing the hair samples and the estimated metal intake through exposure to soil, drinking water, and food consumption. The body burdens of all metals in children at the exposed sites were high, suggesting environmental exposure. Most of the foods consumed resulted in metal intake below the maximum recommended daily intake. However, the net contribution of all food items jointly exceeded the recommended maximum daily intake at some of the exposure sites. Our results further demonstrated that the highest intake of metals occurred via ingestion of high quantities of the cyprinid sh Rastrineobola argentea. Positive linear relationships between the metal body burden in children and estimated daily intake were observed for Cd, Cr, Ti in children consuming high quantity of R. argentea; for Zn and Co in children highly exposed to soils and consuming high quantity of Brassica oleraceae, while Co burden in the body was associated with high consumption of maize meal. This study demonstrated that exposure to soil and consumption of higher quantities of some foods contributed to the increased metal body burdens of children in a geologically exposed region.
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    Dynamics of Metal Uptake and Depuration in a Parasitized Cyprinid Fish (Rastrineobola argentea)
    (Aquatic Taxocology, 2012) Oyoo-Okoth, Elijah; Admiraal, Wim; Osano, Odipo; Kraak, Michiel H. S; Were-Kogogo, Pamela J. A; Gichuki, John; Ngure, Veronica; Makwali, Judith; Ogwai, Caleb
    Infestation of fish by endoparasites may potentially influence metal uptake and elimination by the host. We quantified the metal uptake rate constant (ku) and efflux rate constants (ke) of radiolabeled Cd and Co in the cyprinid fish Rastrineobola argentea experimentally infected with the parasite Ligula intestinalis. During 24 h, the accumulation of Cd and Co increased linearly with no evident steady state in uninfected fish, infected fish and in the parasite. Following aqueous exposures, the ku for Cd in parasites was about 3× higher than that of infected fish and 6× higher than for the uninfected fish. The ku for Co was up to 15× higher in the parasites than that of infected fish and 7.5× higher than for the uninfected fish. The ke for excretion of Cd were consistently higher for the uninfected fish than for the infected fish and also higher for uninfected fish than the parasite. The ke for Co for the uninfected fish was 1.4–2.0× lower than in the infected fish, but higher for parasites compared to uninfected fish (1.3–2.3×). Pulse-chase feeding experiments with radiolabeled copepods showed that Cd assimilation efficiency from food was higher in infected fish, while Co was assimilated more effectively by uninfected fish. The observed differences in metal dynamics between infected and uninfected R. argentea in the laboratory concord with differences in metal concentrations measured in natural populations in Lake Victoria. Our findings provide evidence that L. intestinalis infection enhances Cd accumulation, but depletes the essential Co in the cyprinid fish R. argentea. We conclude that the combined stress of parasites and pollution changes metal risks to fish hosts in a metal specific manner.
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    PCBs in Fish and Their Cestode Parasites in Lake Victoria.
    (Environmental Monitoring and Assessment., 2016) Oyoo-Okoth, Elijah; Oluoch-Otiego, John; Kipkorir, Koross Godfrey Kiptoo; Chemoiwa, Emily J.; Ngugi, Charles C.; Simiyu, Gelas; Omutange, Elijah S.; Ngure, Veronica; Opiyo, Mary A.
    Polychlorinatedbiphenyls(PCBs)areclassified 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 concentration of Σ7PCBs in sediments and fish were 2.2– 96.3 μg/kg dw and 300–3,000 μg/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.
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    Use of The Fish Endoparasite Ligula Intestinalis (l., 1758) in an Intermediate Cyprinid Host (Rastreneobola Argentea) For Biomonitoring Heavy Metal Contamination in Lake Victoria, Kenya
    (Blackwell Publishing Asia Pty Ltd., 2010) Oyoo-Okoth, Elijah; Wim, Admiraal; Osano, Odipo; Kraak, Michiel H. S.; Ngure, Veronica; Makwali, Judith; Orina, Paul S.
    Use of some fish parasites as bioindicators of heavy metal pollution has been demonstrated as a promising approach because of their capacity to bioconcentrate such elements. This study evaluated the effects of a cestode parasite, Ligula intestinalis, on the accumulation of lead (Pb), cadmium (Cd), chromium (Cr) and copper (Cu) in the cyprinid fish, Rastreneobola argentea, in Lake Victoria, Kenya. This L. intestinalis⁄R. argentea model also was assessed as a bioindicator system for heavy metal contamination in the lake. Samples of 125 fish, 63 parasites, water and sediments were collected at four sites in the Kenya portion of the Lake Victoria basin characterized by variable heavy metal concentrations, for ICPOES element analysis. The concentration of all four heavy metals in the fish and parasite samples exhibited site-specific variations relative to the metal concentrations in the water. The Pb, Cr and Cd concentrations in the L. intestinalis were higher than in the fish samples by a factor 11, 18 and 14 respectively, whereas the Cu concentration in L. intestinalis was increased by a factor of 2.5, relative to the Cu concentration in fish. The Pb, Cd and Cr concentrations in the parasite body increased, relative to their concentrations in fish samples, suggesting in the bioaccumulation of these metals by the parasite. The Cu concentration in the fish parasite decreased, relative to increased Cu levels in the fish. This finding was interpreted as being a competition for these elements between the parasite and its fish host. Moreover, the increased Cd and Cr levels in the fish were significantly influenced by the increased abundance of the parasites in the abdominal cavity of the fish samples. Based on the results of this study, the L. intestinalis⁄ R. argentea system is proposed as a promising bioindicator model for evaluating environmental Pb, Cd and Cr concentrations where these species occur.
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    Zooplankton Partitioning in a Tropical Alkaline–Saline Endorheic Lake Nakuru, Kenya: Spatial and Temporal Trends in Relation to The Environment.
    (Lakes & Reservoirs: Research and Management., 2011) Oyoo-Okoth, Elijah; Mucai, Muchiri; Ngugi, Charles C.; Ngure, Veronica; Njenga, Elizabeth W.; Orina, Paul S.; Chemoiwa, Emily C.; Wanjohi, Bernard K.
    Spatial and temporal zooplankton variations were studied for 1 year in tropical alkaline–saline Lake Nakuru to determine how they partition in the habitat, relative to environmental variables. Monthly samples were collected at 10 sampling sites, with subsurface tows, using 33.5-lm mesh plankton nets. Physicochemical parameters displayed clear seasonal variations associated with precipitation patterns. Nine species, belonging to two main zooplankton taxonomic groups (ciliates; rotifers), were identified in the samples. Brachionus dimidiatus dominated the samples, accounting for 80% of the total zooplankton abundance. Kruskall–Wallis tests indicated significant (P < 0.05) temporal and spatial variations among all taxonomic groups. Different zooplankton species displayed a clear succession throughout the year. The total abundance of the rotifers and ciliates peaked at sampling sites near inlets during the long rainy seasons, while those in the inshore sites displayed variable succession patterns. Spatiotemporal structure of the zooplankton assemblages, and its correlation with environmental variables, indicated each species displayed distinct niche-based partitioning. The ciliates niche was associated with increasing soluble reactive phosphorus, total phosphorus and nitrite–nitrogen (NO2–N) concentrations. Niche partitioning in rotifers was associated with nitrate–nitrogen (NO3–N), conductivity and pH. These results indicate physical niche separation, even in a small, relatively homogenous lake among species of rotifers and ciliates, providing information from which future changes in their abundance and spatial distributions can be predicted, given continuous water quality changes.