Impact of Livestock Grazing on Abundance and Community Structure of Macroinvertebrate fauna of Ovia River, Edo State, Nigeria

A survey of the impact of cattle grazing on macro invertebrate fauna of Ovia River was carried out between January and June 2004. Macro invertebrate and water samples were collected from three sampling locations; station I (new grazing area for cattle), station II (initial grazing area) and station III (control location). A total of 33 taxa of macro invertebrates with 831 individuals were encountered in the study. The overall abundance of macro invertebrates was highly significantly different (p<0.01) among the study stations. A posteriori Dunnett’s T3 test showed that the abundance was significantly higher in stations I and III. The low species abundance in station II is an indication of the grazing effect of the herds of cattle, which resulted in the loss of riparian vegetation and eventually the continuous sedimentation of the station during rainfall events. In view of this, governments at all levels should make efforts to establish dedicated pasture lands for livestock grazing across the country.