Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, P.M.B. 1154, Benin City, Nigeria
Ogbeibu, A.E., Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, P.M.B. 1154, Benin City, Nigeria; Anozia, C.A., Department of Animal and Environmental Biology, Faculty of Life Sciences, University of Benin, P.M.B. 1154, Benin City, Nigeria
The effect of dredging on the water quality and rotifers of the Ikpoba River was investigated at four stations-including an upstream control station (station 1). Air and water temperature, and water level were not significantly different (P > 0.05) among the stations. However, transparency, turbidity, flow rate, total suspended solids, total dissolved solids and total solids differed significantly among the stations. The a posteriori Duncan Multiple Range test revealed that transparency was significantly higher (P < 0.001) at station 1 than at the other stations which were not significantly different (P > 0.05), while turbidity was significantly lower at station 1 than the other stations. The total solids (suspended and dissolved) were also significantly lower (P < 0.01) at station 1 than at the other stations which never differed significantly. Among the chemical parameters, only pH, conductivity and iron were significantly different (P < 0.05) among the stations; pH and iron were lower in station 1 than in the other stations while conductivity was significantly higher in station 1 than in the other stations. All the parameters in stations 2, 3 and 4 were not significantly different from one another. With the exception of transparency, flow rate and conductivity, all significant parameters were higher at the dredged stations than at the control station. A total of 12 taxa of rotifers representing 8 families were recorded at station 1, but not a single individual of rotifers was recorded in the dredged stations. Dredging caused many potentially adverse environmental impacts such as change in underwater topography, increase in turbidity and suspended solids concentration, depletion of oxygen content, removal of plants and rotifers. These factors ultimately affected the biological interactions between species at different tropic levels, which was reflected in the rotifer distribution and abundance. © National Institute of Ecology.
