Wildlife & Fisheries management

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End date: 2009Subject: search.filters.subject.Toxicity

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    Hormonal and haematological responses of Clarias gariepinus (Burchell 1822) to nitrite toxicity
    (Medwell Journals, 2007) Ajani, F.; Olukunle, O. A.; Agbede, S. A.
    Study on hormonal and haematological responses of Clarias gariepinus to nitrite toxicity was carried out to know the magnitude of the effects of this stressor on fish physiology. Haematological responses of C. gariepinus to sub-lethal levels of nitrite (0.1 g L-1) at different exposure h (0, 6, 24, 48, 72 and 96 h) were carried out. Blood samples of C. gariepinus were collected at each exposure h and evaluated for primary and secondary stress indicators. Data obtained were subjected to simple descriptive analysis, analysis of variance and Pearson Product Moment correlation analysis. When exposed to nitrite, there was progressive increase in plasma cortisol level of C. gariepinus from 0 h (101.00± 0.10 ng dL-1) to 48 h (161.00± 1.20 ng dL-1), this later decreased at 72 h (107.00±1.60 ng dL-1), it increased in 96 h to 136.00±1.00 ng dL-1. PCV and Hb were elevated after 6 h of exposure and decreased significantly (p<0.05) at 48, 72 and 96 h of exposure in fish exposed to sub-lethal level of nitrite. From the value of 3.69±0.01 106/l recorded at 0 h, RBC level decreased significantly (p<0.05) at 6 h, this was followed by significant increase (p<0.05) at 24 h. The RBC value later decreased gradually to 2.20±0.56 106 L-1 at 96 h. The study shows that hormonal and haematology balances of C. gariepinus was affected on short term exposure to nitrite toxicity.
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    Acute toxicity of ethanol extracts of cocoa bean shell on sarotherodon galilaeus juveniles
    (Medwell Journals, 2008) Olaifa, F. E.; Hamzat, R. A.; Oyetoyan, O. O
    An 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 stocking
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    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.