Browsing by Author "Osano, Odipo"

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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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    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.