ABSTRACT

The haematological changes in juvenile catfish (Clarkis gariepinus exposed to paper mill Ceffluent under field and laboratory conditions were investigated. The study was carried Out at three different sample sites for four weeks, Point A was the Clean reference (served as control), Point B was the effluent receiving site and Point C was the downstream site and accomplished by conducting an indoor study, in which fish were exposed to stream water with a negative control, 40%, 60%, 80% and 100% full strength of effluent for 4 days. They were all replicated. Blood samples from fish indoor study and from caged fish exposed to the river were analyzed for over 30 variables. The physico-chemical parameters of the water, liver and spleen weight of the fish were also determined and examined. Hydrogen ion concentration, dissolved oxygen, hardness, sulphate, chlorine, phosphate, biological oxygen demand, total dissolved solid, Iron and copper showed significant difference from the clean reference area (p<O.05), while zinc, lead and temperature showed no significant difference (p>O. 05).The physico-chemical parameters investigated in the indoor experiment also showed significant difference from the control (p<O.05) though most were within the normal range except for free carbon dioxide which varied from 0.197± 0•02d mg/I in the control tank to 0.475 ± 0.02k mg/I at 100% effluent concentration. The median lethal concentration was found to be 63m1/l and a safe concentration of 6.3m1/l. The haematological and organosomatic index investigated revealed that fish exposed to effluent discharge site (Point B) had lower heamoglobin count, red blood cell count, and packed cell volume, and higher concentrations of mean corpuscular volume, mean corpuscular heamoglobin concentration, mean corpuscular heamoglobin and white blood cell indicating that test fish suffered haemolytic anaemia and Ieucocytosis. Significant difference (p<Z0.05) was also recorded in the blood parameters investigated.There were variations in the values of the blood parameters although values recorded at higher concentration of 60%, 80% and 100% were different from control and did not follow a regular pattern. The organosomatic indices spleensomatic index and hepatosomatic index recorded was found to be significantly different from the control (p<O.05). and fell below the normal range while the field experiment revealed that only spleensomatic index was highly significant from fish exposed to effluent discharge point and the clean reference area, hepatosomatic index was not significantly different from the control (p>O.05). Abnormal behavior such as sudden quick movement, rolling movement, restlessness and then spasm at higher concentrations of 60%, 80% and 100% was also recorded. These results indicate the various effects of paper mill effluents on the haematological parameters. However, the various treatments and site related effects have shown that this effluent poses a big risk on the haematological functions of catfish and physiochemical parameters of the river though few of the parameters fell within the normal ranges for fish culture and in determination of a healthy fish.