Some limnological characteristics of Asejire Lake, Asejire, Southwest Nigeria

Abstract

Asejire Lake is one of the man-made lakes in the southwestern Nigeria. Physico-chemical characteristics of the lake were investigated for eleven months from January to December, 2014. Four sampling stations were established within the lake. Water samples were collected monthly from the four stations. Some limnological parameters were analyzed in-situ with analytical instruments while others were determined in the laboratory using standard laboratory methods. Descriptive and inferential statistics and principal component analysis (PCA) were employed for data analysis. Significant difference (p<0.05) was observed in each month in all the measured parameters during the study period. Mean air temperature was 31.6±0.56˚C with no significant difference (p>0.05) among stations. Highest value of alkalinity, hardness, nitrate and phosphate were recorded in July (107.5 mgCaCO₃/L), May (167.5 mgCaCO₃/L), May (6.9 mg/L) and October (0.52 mg/L), respectively. Electrical conductivity, total dissolved solids, pH, alkalinity, hardness and nitrate were significantly higher (p<0.05) in the wet season than dry season. All the measured water quality parameters were within the recommended WHO standards for drinking water and aquatic life. Two components were identified by PCA; TDS (0.820) and phosphate (0.795). It can be concluded that the lake water is unpolluted and should be protected.

Keywords: water quality, ecosystem, productivity, season, monitoring