Lowland stream restoration by sand addition: Impact, recovery, and beneficial effects on benthic invertebrates

Abstract

Up to now, most lowland stream restoration projects were unsuccessful in terms of ecological recovery. Aiming to improve the success of stream restoration projects, a novel approach to restore sandy-bottom lowland streams degraded by channel incision was launched, consisting of the addition of sand to the stream channel in combination with the introduction of coarse woody debris. Yet it remained unknown whether this novel measure of sand addition is actually effective in terms of biodiversity improvements. The aim of the present study was therefore to evaluate if sand addition can improve hydromorphological stream complexity on the short term leading to an increase in macroinvertebrate biodiversity. To this end, particle transport, water depth, current velocity, dissolved oxygen dynamics, and sediment composition were measured. The response of the macroinvertebrate community composition was determined at different stages during the disturbance and short-term recovery process. Immediately downstream the sand addition site, transport and sedimentation of the sand were initially intense, until an equilibrium was reached and the physical conditions stabilized. The stream section matured fast as habitat formation took place within a short term. Macroinvertebrate diversity decreased initially but recovered rapidly following stabilization. Moreover, an increase in rheophilic taxa was observed in the newly formed habitats. Thus, although sand addition initially disturbed the stream, a relatively fast physical and biological recovery occurred, leading to improved instream conditions for a diverse macroinvertebrate community, including rheophilic taxa. Therefore, we concluded that sand addition is a promising restoration measure for incised lowland streams.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Macroinvertebrate habitat requirements in rivers: overestimation of environmental flow calculations in incised rivers

“…In incised channels, the degree of lateral connectivity of the river and floodplain is reduced, and the degree of modification of the substrate material is higher (Wyżga et al, 2012). As a consequence of channelization and incision, the continuity of the floodplain and shelf zone along the river is disrupted (Walther and Whiles, 2008;Kędzior et al, 2016;Anim et al, 2018;dos Reis Oliveira et al, 2019). Moreover, incision results in a concomitant decrease in sediment supply to the channels, reducing the microhabitat diversity and the quality of macroinvertebrate habitats (Wyżga, 2007;McKenzie et al, 2020).…”

“…In most rivers with an augmented bed, the sedimentation process is disturbed, and thus only habitats located closer to the surface, where lateral erosion occurs, provide a suitable habitat for macroinvertebrates. Modern restoration efforts often involve the artificial addition of sediments to sand (dos Reis, Oliveira et al, 2019) or modification of channel morphology to restore the sedimentation process (Violin et al, 2011;Anim et al, 2018).…”

Comment on hess-2021-196

“…In incised channels, the degree of lateral connectivity of the river and floodplain is reduced, and the degree of modification of the substrate material is higher (Wyżga et al, 2012). As a consequence of channelization and incision, the continuity of the floodplain and shelf zone along the river is disrupted (Walther and Whiles, 2008;Kędzior et al, 2016;Anim et al, 2018;dos Reis Oliveira et al, 2019). Moreover, incision results in a concomitant decrease in sediment supply to the channels, reducing the microhabitat diversity and the quality of macroinvertebrate habitats (Wyżga, 2007;McKenzie et al, 2020).…”

“…In most rivers with an augmented bed, the sedimentation process is disturbed, and thus only habitats located closer to the surface, where lateral erosion occurs, provide a suitable habitat for macroinvertebrates. Modern restoration efforts often involve the artificial addition of sediments to sand (dos Reis, Oliveira et al, 2019) or modification of channel morphology to restore the sedimentation process (Violin et al, 2011;Anim et al, 2018).…”

Transplanting macrophytes as a rehabilitation technique for lowland streams and their influence on macroinvertebrate assemblages

“…Therefore, it is necessary to improve this technique for future restoration projects. Moreover, it is important to evaluate the ecological status of watercourses after rehabilitation; for this purpose, macroinvertebrates are considered good indicators of changes in the environment (Bonada et al 2006, dos Reis Oliveira et al 2019). This assemblage is an essential component of the aquatic ecosystem because contribute to the processing of particulate organic matter, regulating primary production and providing food for fishes (Reece & Richardson 2000, Spänhoff & Arle 2007.…”