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River restoration enhances not only habitat diversity in the stream channel and riparian zone, but also retention of organic matter, which together are expected to enhance aquatic-terrestrial linkages, and the range of autochthonous and allochthonous resources. Consequently, alterations of food-web structure and trophic relationships can be expected. We applied stable isotope analysis (δC, δN) to characterize changes in the trophic structure of benthic invertebrate communities between paired restored and unrestored river reaches across 16 European catchments. We sampled dominant taxa of invertebrate assemblages belonging to different functional feeding groups and calculated δC range to estimate the diversity of basal resources assimilated, δN range as an indicator of the trophic length and standard ellipse area corrected for small samples as a measure of isotopic niche width. We analysed (1) if restoration influences the trophic structure of invertebrates, (2) if effects of restoration depend on the extent of restoration effort, and (3) if effects of restoration depend on restoration measures applied. Our European-scale comparison indicates that river habitat restoration effects trophic structure, primarily by increasing the breadth of resources assimilated by consumers; this effect increases with restoration effort and it depends on restoration measure type. [ABSTRACT FROM AUTHOR]

Evidence of freshwater biodiversity decline, species extinction and severe alterations in the biological structure and function of freshwater ecosystems is accumulating. Here we explore the role of macrophyte diversity in lowland streams for the abundance, taxon richness and composition of macroinvertebrate communities also including the abundance of different functional feeding groups. We applied a controlled in situ experiment in four small lowland stream reaches situated in rural landscapes in Denmark. We were able to explain a major fraction of the variability in the macroinvertebrate communities by differences in total macrophyte surface areas among treatments, but the number of macrophyte species in the experimental treatment also played a highly significant role (i.e. one, two or three plant species) for both the abundance, richness and composition of the macroinvertebrate community. We strongly encourage managers to protect plant diversity in streams, not only because the plants themselves constitute an important part of the biodiversity, but also because they positively affect the macroinvertebrate community. Moreover, macrophyte-friendly management can be seen as a nature-based solution to mitigate the degraded physical conditions characterising many streams in agricultural catchments. [ABSTRACT FROM AUTHOR]