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The positive effect of mitigation measures on in-stream habitat conditions and the benthic community is recognised. In heavily modified rivers, though, the response of aquatic invertebrates to mitigation measures and habitat mosaic changes is scarcely documented. We used non-metric multidimensional scaling to explore the benthic community of leveed rivers in the agricultural lowlands of Northern Italy. The relevance of in-stream substrate microhabitat for the benthic community was assessed, together with the impact of mitigation measures. We proposed a straightforward approach to quantify similarity of microhabitat mosaic between sites testing its statistical significance based on Bayesian statistics. We hypothesised that changes of microhabitat mosaic would reflect the level of implementation of mitigation measures and benthic invertebrates would respond accordingly. Alpha, beta diversity and benthic metrics used to classify ecological status/potential were considered and their variation tested against different levels of measure implementation. Lastly, ecological potential classification was paralleled to both the level of measure implementation and habitat attributes. The microhabitats found at sites where measures were fully implemented differed from those observed elsewhere and they clearly mirrored morphological alteration and mitigation measures. Moreover, alongside morphological alteration, microhabitat diversity and mosaic were the main factors for benthic community structure. While benthic beta diversity strictly reflected microhabitat diversity, alpha diversity and ecological status metrics copied the mosaic gradient. Microhabitat attributes and most benthic metrics showed significant changes following measure implementation and they were accompanied by a gradual shift in ecological potential classes. We demonstrated the importance of in-stream substrate microhabitats as a bridge between mitigation measures and the benthic community. Particularly when ecological classification is under focus, microhabitat mosaic should be evaluated for achieving a better understanding of biological responses. The huge amount of data available worldwide could support a straightforward use of river mosaic information for river management., (Copyright © 2019. Published by Elsevier B.V.)

We hypothesized that reach-scale, bank and channel modification would impact benthic communities in temporary rivers of Sardinia, when pollution and water abstraction are not relevant. A range of variables were considered, which include both artificial structures/alterations and natural features observed in a stream reach. Multivariate regression trees (MRT) were used to assess the effects of the explanatory variables on invertebrate assemblages and five groups, characterized by different habitat modification and/or features, were recognized. Four node variables determined the splits in the MRT analysis: channel reinforcement, tree-related bank and channel habitats, channel modification and bank modification. Continuity of trees in the river corridor diverged among MRT groups and significant differences among groups include presence of alders, extent of channel shading and substrate diversity. Also, the percentage of in-stream organic substrates, in particular CPOM/Xylal, showed highly significant differences among groups. For practical applications, thresholds for the extent of channel reinforcement (40%) and modification (10%) and for bank alteration (≈30%) were provided, that can be used to guide the implementation of restoration measures. In moderately altered river reaches, a significant extent of tree-related habitats (≈5%) can noticeably mitigate the effects of morphological alteration on aquatic invertebrates. The outcomes highlight the importance of riparian zone management as an opportune, achievable prospect in the restoration of Mediterranean temporary streams. The impact of bank and channel modification on ecological status (sensu WFD) was investigated and the tested benthic metrics, especially those based on abundance data, showed legible differences among MRT groups. Finally, bank and channel modification appears to be a potential threat for the conservation of a few Sardo-Corsican endemic species. The introduction of management criteria that openly use information on endemic species seems crucial to reduce the risk of improving overall ecological status while depleting biodiversity., (Copyright © 2016 Elsevier B.V. All rights reserved.)