Wildlife & Fisheries management

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Author: search.filters.author.Olaifa, F. E.Subject: search.filters.subject.Heavy metals

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    Bioassay using the water soluble fraction of a Nigerian light crude oil on clarias gariepinus fingerlings
    (Physiological Society of Nigeria, 2012) Olaifa, F. E.
    A 96-hour bioassay was conducted using the water soluble fraction of a Nigerian light crude oil sample on Clarias gariepinus fingerlings. 0, 2.5, 5.0, 7.5 and 10 mls of water soluble fractions (WSF) of the oil were added to 1000 litres of de-chlorinated tap water to form 0, 25, 50 , 75 and 100 parts per million representing treatments 1 to 5 respectively. Each treatment had two replicates with fifteen fish per replicate. At the end of the 96-hour period of exposure, the fish were transferred into separate bowls containing fresh water without oil for recovery for ten more days. Heavy metal and total hydrocarbon contents of the water and fish were analyzed at 96 hour and 14 days which marked the end of the recovery period. No mortalities were recorded on all treatments during the 96-hour period. Mortalities were observed between 120 and 144 hours after the onset of the experiment with the maximum number of dead fish (p<0.05) from treatment 5(100 ppm WSF) during the recovery period indicating a delayed response to the WSF by the fish. No mortalities were recorded after 144 hours till the termination of the experiment at 14 days . The 96-hour LC50 could not be calculated since no deaths occured during the period. The Total hydrocarbon contents of the water were 0, 0.026 ,0.316 ,0.297, 0.253 mg/l for treatments 1(0 ppmWSF)) to 5(100ppmWSF) respectively. Lead , iron and cadmium were not detected in water during the study, lead was also not detected in fish muscles from all treatments. The iron contents of all the treatments were lower than the control except for treatment 3(50 ppm WSF). THC concentrations in fish were higher at 96 hours and 14days than in the water indicating bioconcentration in fish and a retention in the fish long after exposure.
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    Presence of hydrocarbons and heavy metals in some fish species in the cross river, Nigeria.
    (2004) Olaifa, F. E.; Ayodele, I. A.
    The study was undertaken to determine the total hydrocarbon (THC) and heavy metal contents of fish (finfish and shelf fish) in the cross river, Nigeria. Fish samples were collected in the dry (March) and rainy (October) seasons between 2000-2002. The finfish species identified in the study were Synodontis clarias, Sarotherodon galilaeus, Heterotis niloticus, Scholbe mystus, ansorgil and the shelfish were macrobrachium vollenhovonii and tympanotnomus luscalus. Significant difference (P<0.05) existed between finfish andshellfish in both THC and heavy metals contents. The levels of THC in fish exceeded the World Health Organization's limit of 0.0001 ppm by an average of 3.2 and 15.57 mg/kg in fin and shelffish respectively. High concerntrations of vanadium and THC in fish samples were the main indicators of pollution from petroleum sources
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    Heavy metal contamination of clarias gariepinus from a lake and fish farm in Ibadan, Nigeria
    (Ibadan Biomedical Communications Group, 2004) Olaifa, F. E.; Olaifa, A. K.; Adelaja, A. A.; Owolabi, A. G.
    Adult Clarias gariepinus (African Catfish) were purchased from Eleiyele Lake and Zartech fish farm in Ibadan. Water samples were also collected in February (dry season) and June (rainy season), 2002. Gill, bone, intestine, muscle and water samples were analyzed for five metals: manganese, copper, zinc, iron, and chromium by atomic absorption spectroscopy (AAS) in two separate experiments. In each case, two tissues were compared with the levels of the metals in water viz: Gill, bone, and water; intestine, muscle and water. Generally, lower concentrations of the metals were recorded in water than fish tissues. Higher concentrations of zinc than recommended by the Federal Environmental Protection Agency were recorded in the fish during the dry season. Iron was the dominant metal in the muscle while Chromium was the least. Significant differences (p<0.05) were recorded in copper and zinc concentrations in the muscle, intestine and water during the dry and rainy seasons .In gill, bones and water, significant differences (p<0.05) were only recorded for the two stations for copper during the rainy season and only zinc was significantly different (p<0.05) in the dry season. It was concluded that though the heavy metals of interest were present in measurable quantities there were still within safe limits for consumption