Two further studies document how the selection of alternative methodological approaches and multi-criteria assessment tools can lead to different conclusions regarding design and development of small hydropower projects. Their findings stress the danger linked to direct application of results from flume investigations and call for more on-site experiments and monitoring. Unexpectedly, they find that macroinvertebrate abundance and composition do not vary between peaks, but considerable differences in the drift were found between pools and riffles. experimentally analyze the response of drifting and benthic macroinvertebrate communities to consecutive hydropeaking events generated by a small hydropower installation. An exemplary application of the collected information by means of a mesoscale habitat simulation model demonstrate their value for predicting fish distribution in a hydropower impacted river reach.

They find scarce information for one third of them, especially for the most threatened endemic species during the critical spawning period.

review the current knowledge of physical habitat preferences of more than thirty freshwater fish species which populate Italian rivers. Two studies examine different facets of riverine ecology. The articles in this research topic effectively showcase the multidisciplinary expertise required to achieve these goals. Such a mechanistic understanding and the availability of tools to integrate this knowledge into spatial planning and design processes may indeed promote sustainable tradeoffs between the preservation of ecosystem functions and energy production by means of small hydropower ( Basso et al., 2020). A better comprehension of the individual as well as the cumulative impacts of small hydropower on riverine ecosystems is one of the most important global issues for environmental conservation ( Sutherland et al., 2020). Whereas knowledge of environmental threats posed by dams informs advocacy and solutions for more sustainable large hydropower ( Winemiller et al., 2016), awareness of the peculiar effects of small hydropower on hydrological and ecological dynamics is still forming ( Lange et al., 2018). Small hydropower plants are often built in pristine river basins which can be hotspots of biodiversity, and in cascade installations with disturbances replicated along river courses. The global proliferation of small hydropower is fostered by the international agenda and national strategies on renewable energy, its importance for rural communities not connected to centralised electricity services and its contribution towards meeting renewable energy targets ( Couto and Olden, 2018).

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