Effect of a Glyphosate (N-(Phosphonomethyl) glycine) Application To ControlEichhornia crassipesMart. on Fish Composition and Abundance in Abiala Creek, Niger Delta, Nigeria

Roundup, a commercial preparation containing 360 g/l glyphosate in the form of 480 g/l isophropylamine salt was applied to control water hyacinth (Eichhornia crassipesMart.) in Abiala creek, Delta State, Nigeria. The herbicide, which was applied at a rate of 2·88 kg a.e./ha on a heavily infested stretch of the creek, succeeded in killing mats of water hyacinth in the treated plots within 7 days after treatment. The presence of floating aquatic vegetation caused a low fish catch in the untreated control plots during the period of study. The population of fish specimens caught in the glyphosate-treated plots increased significantly (P<0·5) after treatment. The presence of juveniles and immature adult fishes in the treated areas of the creek indicated that the impaired water quality had been adequately regenerated 28 days after treatment.