| Abstract: | 1. The biological effectiveness of a series of artificial riffles constructed from cobble-sized local material in the channelized Harper's Brook (Northamptonshire, England) was measured by comparing the macroinvertebrate communities of three new riffles with a control natural riffle upstream, and with three original channelized stretches (runs). 2. The mean diversity of macroinvertebrates in the seven sites was significantly different: diversities of the natural riffle and two shallower artificial riffles were highest, whilst those of the other deeper, artificial riffle and the three channelized runs were lowest. 3. There was significant negative correlation between diversity and depth; significant positive correlation between diversity and velocity. 4. Artificial riffles, if correctly constructed, do improve the habitats and increase biodiversity of macroinvertebrates to levels similar to a natural riffle. A minimum velocity of 40 cm s−1 and maximum depth of 25 cm is necessary during low-flow discharges for artificial riffles to function biologically as natural riffles. © 1997 John Wiley & Sons, Ltd. |
