The biological effectiveness of artificial riffles in river rehabilitation

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.

Global Review of the Physical and Biological Effectiveness of Stream Habitat Rehabilitation Techniques

“…, ), ), ), and others demonstrated an increase in macroinvertebrate abundance after instream habitat improvement. Other studies detected an increase in some functional feeding groups but not others (i.e., ; Gortz 1998), or they detected an increase in macroinvertebrate diversity (Ebrahimnezhad and Harper 1997; ). Conversely, many other studies (e.g., ; Hilderbrand et al 1997; Laasonen et al 1998; Larson et al 2001; ; Roni et al 2006b) detected no difference in macroinvertebrate density or diversity in enhanced (by addition of various boulder and log structures) and untreated stream reaches.…”

“…Tarzwell (1937Tarzwell ( , 1938, Gard (1961), Haapala et al (2003), and others demonstrated an increase in macroinvertebrate abundance after instream habitat improvement. Other studies detected an increase in some functional feeding groups but not others (i.e., Wallace et al 1995;Gortz 1998), or they detected an increase in macroinvertebrate diversity (Ebrahimnezhad and Harper 1997;Harper et al 1998).…”

Fish assemblage change following the structural restoration of a degraded stream

“…Contrary to our expectations, we found no significant linkage between the restoration project and trophic guilds. This is likely driven by interannual variation in the macroinvertebrate community as it was in flux in response to changes in geomorphology (Ebrahimnezhad & Harper, 1997;Edwards et al, 1984;Harper, Ebrahimnezhad, Climent, & Cot, 1998).…”

City Channel Chironomids-Benthic Diversity in Urban Conditions

“…Some studies have shown a rapid increase in invertebrate diversity and density to a circa‐stable level, in some cases within 4 years (Wallace et al ., ; Ebrahimnezhad and Harper, ; Friberg et al ., ). Adding habitat features, such as logs or artificial riffles, can result in an almost immediate restoration of diverse aquatic communities (Wallace et al ., ; Ebrahimnezhad and Harper, ; Haapala et al ., ), whereas reconfiguring the stream channel may cause an initial decrease in macroinvertebrate diversity and density (lasting 1–4 years) because of a temporary disruption of their physical habitat (Friberg et al ., ; Lorenz and Jahnig, ; Tullos et al ., ). While those studies have shown a rapid response in the invertebrate fauna, others have shown no detectable difference between the restored and unrestored reaches (Roni et al ., ).…”

“…An increase of habitat complexity should influence diversity of invertebrates (Tullos et al, 2009;Lencioni et al, 2012); however, the actual response of invertebrates has varied widely (Roni et al, 2008). Some studies have shown a rapid increase in invertebrate diversity and density to a circa-stable level, in some cases within 4 years (Wallace et al, 1995;Ebrahimnezhad and Harper, 1997;Friberg et al, 1998). Adding habitat features, such as logs or artificial riffles, can result in an almost immediate restoration of diverse aquatic communities (Wallace et al, 1995;Ebrahimnezhad and Harper, 1997;Haapala et al, 2003), whereas reconfiguring the stream channel may cause an initial decrease in macroinvertebrate diversity and density (lasting 1-4 years) because of a temporary disruption of their physical habitat (Friberg et al, 1998;Lorenz and Jahnig, 2009;Tullos et al, 2009).…”