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

Igiobe Aganmwonyi,Fasipe Iriabgonse,Chukwudi Emeribe

doi:10.4314/jasem.v19i4.27

Abstract

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.

Highlights

Land-use practices, such as widespread deforestation and alteration of natural vegetation for forestry, agriculture, livestock grazing and urban land-use, has potential to influence the condition of our freshwater ecosystems and biota (Collier and Quinn 2003; Thompson and Townsend 2003; Allan 2004; Jones et al 2011; Virbickas et al, 2011)
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
The objective of this study is to investigate the impact of livestock grazing on the abundance of macroinvertebrates in both E. crassipes and littoral sediment biotope

Summary

Introduction

Land-use practices, such as widespread deforestation and alteration of natural vegetation for forestry, agriculture, livestock grazing and urban land-use, has potential to influence the condition of our freshwater ecosystems and biota (Collier and Quinn 2003; Thompson and Townsend 2003; Allan 2004; Jones et al 2011; Virbickas et al, 2011) These practices generally result in significant loss or change of terrestrial and riparian vegetation, increased fine sediment loads, increased nutrient and chemical inputs, altered temperature and hydrological regimes and loss of large woody debris into nearby streams (Thompson and Townsend 2003; Allan 2004; Extence et al, 2013). Land-use change significantly impact on stream macroinvertebrate communities, often causing a shift towards more pollution tolerant taxa such as Diptera (Chironomidae), Mollusca and Oligochaeta dominating the system and a decline in pollution sensitive taxa such as Ephemeroptera, Plecoptera and Trichoptera (Harding et al 2000; Kenney et al., 2009).

Objectives

Methods

Results