The impact of land based pollutants on the non-insect benthic phytomacrofauna and water quality in Epe
lagoon was investigated between September, 2004 and February, 2005. Five study stations impacted by land based
pollutants were selected upstream along the course of the Lagoon. The study showed that land based pollutants
caused a decrease in dissolved oxygen and pH and an increase in biochemical oxygen demand (BOD) and
phosphates. Significant differences in these parameters were established among the stations sampled. A post hoc test
indicated that stations 2, 3, and 4 were mostly impacted by pollutants. A generally low taxa population and diversity
were recorded in this study. Eight taxa were identified from a total of 65 individuals collected from the five stations
along the lagoon. No organism was recorded in station 3.The analyses showed that the overall abundance of fauna
differed significantly among the stations. Analysis of variance showed that the abundance of Lymnaeidae was
significantly higher (P<0.05) than those of the other families. The dominance of the taxa Lymnaeidae was a clear
indication of pollution which resulted in a decline and total elimination of other benthic macroinvertebrates, which
are intolerant of the effects of polluting effluents. This study suggests that the response of benthic phytomacrofauna
is important in the study of impacted aquatic systems.