The role of benthic microhabitats in determining the effects of hydromorphological river restoration on macroinvertebrates

Abstract

Despite the large number of river restoration projects carried out worldwide, evidence for strong and long-term positive ecological effects of hydromorphological restoration on macroinvertebrates is scarce. To improve the understanding of the success and failure of restoration measures, a standardized field study was carried out in nineteen paired restored and degraded river sections in mid-sized lowland and mountain rivers throughout Europe. We investigated if there were effects of restoration on macroinvertebrate biodiversity, and if these effects could be related to changes in microhabitat composition, diversity and patchiness. Effects were quantified for all taxa combined, as well as Ephemeroptera, Plecoptera and Trichoptera separately. Additionally, species trait classifications of microhabitat preference types were used as a functional indicator. Restoration had no overall positive effects on the selected macroinvertebrate metrics. Rather, we did find positive relationships between the macroinvertebrate responses and the effect of restoration on the diversity and patchiness of microhabitats. Furthermore, the effects on macroinvertebrates could be related to changes in the cover of specific substrate types in the restored sections. We conclude that the limited effect of restoration on macroinvertebrate diversity overall reflected, at least in part, the limited effect of most restoration measures on microhabitat composition and diversity.

Evaluating good-practice cases for river restoration across Europe: context, methodological framework, selected results and recommendations

“…even small patches may already have a positive effect (see . Moreover, macroinvertebrate richness depended on microhabitat diversity (see Verdonschot et al, 2015). Since restoration projects had no significant effect on microhabitat diversity (see Poppe et al, 2015), this may at least partly explain the missing effect of restoration on macroinvertebrate richness and diversity (see Verdonschot et al, 2015).…”

“…Moreover, macroinvertebrate richness depended on microhabitat diversity (see Verdonschot et al, 2015). Since restoration projects had no significant effect on microhabitat diversity (see Poppe et al, 2015), this may at least partly explain the missing effect of restoration on macroinvertebrate richness and diversity (see Verdonschot et al, 2015). These results indicate that although projects restoring river planform by widening or remeandering might increase macro-and mesoscale habitat conditions and hence are visually appealing, they often fail at increasing microhabitat diversity relevant for organism groups like macroinvertebrates.…”

First signs of macroinvertebrate recovery following enhanced restoration of boreal streams used for timber floating

“…Indeed, higher physical complexity has been related to higher biodiversity in near-natural systems, and losses of biodiversity have been documented for degraded systems with reduced physical complexity (Beisel et al 2000, Passy andBlanchet 2007). Similarly, follow-up studies of habitat restorations in streams and rivers have found that although physical complexity is frequently enhanced, this has often failed to generate the desired responses within target organism groups or ecosystem functions (Pretty et al 2003, Lepori et al 2005, Nilsson et al 2017, though examples of more successful outcomes exist (Miller et al 2010, Verdonschot et al 2016, Frainer et al 2017. Similarly, follow-up studies of habitat restorations in streams and rivers have found that although physical complexity is frequently enhanced, this has often failed to generate the desired responses within target organism groups or ecosystem functions (Pretty et al 2003, Lepori et al 2005, Nilsson et al 2017, though examples of more successful outcomes exist (Miller et al 2010, Verdonschot et al 2016, Frainer et al 2017.…”

Benthic and hyporheic macroinvertebrate distribution within the heads and tails of riffles during baseflow conditions

“…The distribution of invertebrates in lotic ecosystems is typically patchy, often reflecting spatial patterns which are structured around physical, chemical and trophic processes (Silva et al, 2014;Gibbins et al, 2016;Verdonschot et al, 2016). Research examining lotic environments has typically focussed on longitudinal and lateral gradients (environmental and ecological) as exemplified through the river continuum (Vannote et al, 1980;Rosi-Marshall et al, 2016) and flood pulse concepts (Junk et al, 1989;Turić et al, 2015).…”