Physico-chemical parameters of Ikere-Gorge, Iseyin, Oyo State, Nigeria

Abstract

Water quality determines the distribution of aquatic organisms within aquatic ecosystem. Deterioration of water quality is of a great concern in  freshwater ecosystem because of its adverse effects on freshwater organisms. Therefore, the physico-chemical parameters of Ikere-gorge were examined in this study to determine its suitability for fish production. Air and water temperature, transparency, electrical conductivity and total
dissolved solids were determined in-situ. Dissolved oxygen, alkalinity, hardness, phosphate and nitrate were determined with standard analytical methods. The selected parameters examined in this study were determined monthly between January 2017 and December 2018. The mean monthly values of physico-chemical parameters of Ikere-gorge obtained are as follows: air temperature (27.46±1.82 ºC), water temperature (28.14±1.57 ºC), pH (6.50±0.63), water transparency (1.34±0.12 m), dissolved oxygen (5.93±0.29 mg/L), electrical conductivity (130.59±7.59 μS/cm), total dissolved solids (67.67±4.37 mg/L), total hardness (56.70±15.76 mg/L), total alkalinity (58.97±9.53 mg/L), total phosphate (2.22±0.67 μg/L) and nitrate  (2.90±1.23 μg/L). Likewise, it was observed that surface water temperature had negative significant relationship with dissolved oxygen at P < 0.05.
Transparency has negative significant relationship with phytoplankton abundance at 0.05 (P ˂ 0.05) and with phosphate and nitrate at 0.01 significant level. The annual mean of Trophic Status Index based on total phosphate is 15.04±1.63. This classified Ikere-gorge trophic status as mesotrophic at stage 2. The result of this study reveals the mesotrophic status of Ikere-gorge and water quality are within the ranges recommended  for fish production and should be adequately managed for sustainable fish production.

Keywords: Aquatic organisms, Ecosystem, Freshwater, Trophic state, Abundance