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Application of a fish health assessment index and associated parasite index on Clarias gariepinus (sharptooth catfish) in the Vaal River system, with reference to heavy metals

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dc.contributor.advisor Prof. A. Avenant-Oldewage en_US
dc.contributor.author Crafford, Dionne
dc.date.accessioned 2012-08-27T13:30:26Z
dc.date.available 2012-08-27T13:30:26Z
dc.date.issued 2012-08-27
dc.date.submitted 2000
dc.identifier.uri http://hdl.handle.net/10210/6667
dc.description M.Sc. en_US
dc.description.abstract The Vaal Dam subcatchment is located in the upper reaches of the Vaal River. As a result the water quality is reasonably good. In contrast the Vaal River Barrage catchment includes the PWV area, resulting in poorer water quality. During this study, a fish Health Assessment Index (HAI) successfully tested in previous studies on the Olifants River System was applied to the Vaal River System. The aim was to determine if the HAI could distinguish between the Vaal Dam and Vaal River Barrage with regards to water quality. Surveys were conducted bimonthly from November 1998 to February 2000. Physical water quality variables were measured. Water and sediment samples were also collected and analyzed (Institute for Water Quality Studies, Department of Water Affairs and Forestry) to verify the HAI results. Rand Water Board and the Department of Water Affairs and Forestry also made water quality data available. Twenty sharptooth catfish, Clarias gariepinus, were collected from both localities with the aid of gill nets. Fish were checked for external parasites on the boat. On land fish were weighed and measured, after which blood was drawn and slime smears made. Blood and slime smears were examined under a light microscope for parasites. The HAI examination was performed after severing the spinal cord. Internal parasite numbers were recorded. From the parasite data collected infestation statistics were calculated. Four variations of the Parasite Index (PI) were incorporated in the HAI and results compared. During each survey gill arch, gill filament, muscle, skin and liver tissues were collected from each fish. These were analyzed for strontium, aluminium, chromium, manganese, iron, lead, copper, zinc and nickel concentrations using atomic absorption spectrophotometry. Differences in water and sediment trace metal concentrations between localities were small. Metal concentrations in fish tissues recorded from both localities were also almost identical. Possible explanations for this trend were discussed in the relevant section. Highest metal concentrations were generally recorded in gill tissue followed by liver, skin and muscle. Physical water quality variables (salinity and conductivity), and macro water analysis (e.g. phosphate and nitrate) indicated that water quality at the Vaal River Barrage was poorer. The HAI confirmed this. Higher index values were recorded from the Vaal River Barrage, with the converse being true for the Vaal Dam. Regression analysis indicated that plasma protein, haematocrit and the index value obtained using the Inverted Parasite Index, most successfully predicted (70 %) from where a randomly chosen fish were collected. When viewing index values obtained using the four versions of the PI, all four distinguished between localities. The discriminatory ability of the Inverted PI was slightly higher than that of the other PI's. It is concluded that the HAI distinguished successfully between the Vaal Dam and Vaal River Barrage on the grounds of water quality. Poor fish health correlated with decreasing water quality (salinity and eutrophication). en_US
dc.language.iso en en_US
dc.subject Metal wastes - Research - South Africa - Vaal River en_US
dc.subject Effect of heavy metals on fishes - Research - South Africa - Vaal River en_US
dc.subject Effect of heavy metals on Clarias gariepinus - Research - South Africa - Vaal River en_US
dc.title Application of a fish health assessment index and associated parasite index on Clarias gariepinus (sharptooth catfish) in the Vaal River system, with reference to heavy metals en_US
dc.type Thesis en_US


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