Physico-Chemical Parameters, Plankton, Macrozoobenthos And Fish Fauna Of Ibuya River, Sepeteri, South-Western Nigeria

ABSTRACT

Ibuya River runs across the Old Oyo National Park, a wildlife and recreational park. There is paucity of information on the limnology of the river which will provide information on the ecological status relevant for sustainable management. Therefore, this study was carried out to investigate the physico-chemical parameters, diversity and abundance of plankton, macrozoobenthos and fish fauna of Ibuya River.

Surface water (72), plankton (72) and macrozoobenthic (72) samples were collected monthly from September 2012 to February 2014 at randomly selected stations (i-iv) along the river. Water temperature, pH and Dissolved Oxygen (DO) were measured in situ, while hardness, turbidity, phosphate (PO₄3˗), sulphate (SO₄2-), heavy metals including cadmium (Cd), Iron (Fe) and lead (Pb), were determined in the laboratory according to APHA method. Plankton samples were collected with plankton net (mesh size, 55μm), identified and counted microscopically. Macrozoobenthos were collected with Van-Veen grab (0.086 m2), identified and counted macroscopically. Fish samples were collected with gill net (mesh size 45mm), identified and counted. All identifications including pollution indicator species were done using standard identification keys. Species diversity was determined with Shannon-Wiener index HI. Descriptive statistics, student t-test, one-way ANOVA, Pearson correlation coefficient and Principal Component Analysis (PCA) were used for analysis of data at α0.05.

Water temperature was24.8±0.2 °C; pH, 7.60±0.04; DO, 4.4±0.2 mg/L; hardness, 39.6±2.1 mg/L CaCO3; turbidity, 19.4±0.9 FTU; Cd, 0.2±0.1 mg/L; Pb, 0.7±0.1 mg/L; Fe, 2.1±0.2 mg/L; PO₄3˗, 24.3±2.8 mg/L; and SO₄2-, 31.8±3.1 mg/L. Turbidity had significant spatial and seasonal variation at p