Wildlife & Fisheries management
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Item 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.Item Acute toxicity of ethanol extracts of cocoa bean shell on sarotherodon galilaeus juveniles(Medwell Journals, 2008) Olaifa, F. E.; Hamzat, R. A.; Oyetoyan, O. OAn acute toxicity test of ethanol extract of cocoa bean shell (CBS), a by-product of cocoa processing was conducted on 250 Sarotherodon gallilaeus juveniles for 96 h. There were 5 treatments and one control with each having 3 replicates. The treatments were prepared as 10,000, 7500, 4167, 2315, 1286 and 0 mg L-1 (control). The aim of the experiment was to study the toxic effects of Ethanol extract of CBS. While, the control experiment produced no mortalities and adverse histopathological responses, there were reactions to the presence of CBS extract in all the treatments which included restlessness and mortality. The lethal concentrations at which fifty percent of the test population died (LC 50) obtained using the logarithm method were 7943, 5012 and 6310 mg L-1 for replicates 1, 2 and 3, respectively while the probit method gave 5878, 4865, 6103 mg L-1 for replicates 1, 2 and 3, respectively. Histopathological examination of control fish showed no lesions on all tissues examined. However, marked changes were observed in the liver in form of degenerative hepatocytes, multifocal aggregation of haemosiderin laden macrophages; in the gills as shortening of gill filaments and in the brain as spongiosis of white cerebral matter of fish subjected to various concentrations of CBS extract. It was concluded that ethanol CBS extract possessed piscicidal properties on S. gallilaeus which could be useful in culling stunted and unwanted fish populations from ponds before stockingItem Assessment of Toxicological impact of light crude oil on clarias gariepus (Burechell, 1822) fingerlings(2005) Olaifa, F. E.Oil spillage is of critical concern in Nigeria because of the problems of pollution and associated disturbances. It is therefore necessary to study the effects of oil pollution on fish using clarias gariepinus, a widely cultured fish species in the tropics. A short-term (96-hours), statics bioassay was carried out to determine the toxicity of crude oil (qua ibeo light) on C. gariepinus fingerlings. The biossay involved five treatment viz:0, 25, 50, 75, and 100µL/L. The water and fish samples were analyzed for total hydrocarbon content (THC) and heavy metals at the end of the experiment. There were significant differences (p<0.05) among the five treatments. The LC50 ( concentration at which 50 percent of the test population died) was 1.58µL/L. Lead, iron, cadmium and chromium were not detected in the water contaminated with the crude oil sample.