The effects of urban perturbations on the benthic macroinvertebrates of a southern Nigerian stream

All physical and chemical conditions except pH and temperature were significantly different at the upstream control station (1) and urban stations (2, 3, 4) reflecting the perturbational stress. For the numbers of macroinvertebrate taxa occurring in the bank-root biotope, the stations are ranked as 1>3>2>4; for abundance the order of stations is 2=4>1=3. Stations 2 and 4 indicated the effects of urban stress; station 3 represented recovery between stations 2 and 4. In the erosion biotope, both numbers of taxa and their abundance progressively reduced from station 1 to 4. In the bank-root biotope, a tubificid species and chironomids were most tolerant to stress; despite the reduction in numbers of taxa, their abundance was high. In the erosion biotope, one tubificid taxon was common along with low numbers of chironomid, syrphid and tabanid larvae. -from Authors