Aspects Of Meteorological Factors And Temperature Regime Of Asa Lake, Ilorin Nigeria

Abstract

The temperatures of Asa lake were studied for 12 months at three sites along the lake between the early morning and afternoon hours. Surface water temperatures were generally higher than the air temperatures during the afternoon hours except in the months of January to March when air temperatures were high (28.1 to 28.70C) due to the low relative humidity (39 to 70 %). In the morning hours, surface water temperatures (25.5 to 26.30C) became higher than the air temperatures (25.2 to 26.00C) from May to December when relative humidity values were also high (50 to 88 %). The difference (P < 0.05) in the surface and bottom water temperatures were generally higher (0.7 to 3.10C) in the afternoon than in the morning hours (0.2 to 0.80C) due to the effect of sunlight. Also the temperature difference (P < 0.05) in the surface and bottom waters were usually higher at the dry season than the wet season for similar reasons. Thermally stratified conditions were more pronounced in the afternoon than in the morning hours especially from January to August. These conditions were not clearly defined as from October / November when water temperatures from surface to about 9 meters deep were almost uniform (mean =26.50C) due to the mixing effect. Minimum and maximum water temperatures were significantly different (P < 0.05) for both surface and bottom waters. However there were no marked variations in the temperature pattern along the three sampling sites. It was concluded that the fish species distribution with respect to the temperatures along the lake may show little or no variation. Keywords: Temperatures, Asa lake, meteorological factor, relative humidity, Thermal stratifications The Zoologist Vol. 5 2007: pp. 39-46