Author(s): Linda Rojning; Asa Widen; Kerstin Holmgren; Johan Ostergren

Linked Author(s):

Keywords: Macrophytes; Littoral habitats; Reservoir management; Lake-in-Reservoirs; Nature-based solutions

Abstract: While h ydropower is an important source of low-carbon electricity around the world, its operation can also come with considerable ecological consequences. The often large and unnatural fluctuations in water levels that occur in regulated lakes and reservoirs are one of the main issues, as these variations have been shown to damage littoral habitats, reduce biodiversity, and disrupt key ecological processes. To help soften these impacts, shallow sub-basins known as Lake-in-Reservoirs (LiRs) have been constructed in some Scandinavian reservoirs. By maintaining water levels closer to natural conditions, LiRs are intended to provide refuge for species sensitive to water-level fluctuations. Nonetheless, evidence of their ecological effectiveness is still limited and warrants closer examination. In this ongoing study, we explore the ecological potential of LiRs by comparing macrophyte communities across three LiRs, four natural lakes, and a hydropower-regulated reservoir in northern Sweden. While overall species richness did not differ significantly between lake types, comparisons of individual lakes revealed variation . Notably, two LiRs supported significantly more macrophyte species than the regulated reservoir. These preliminary results suggest that LiRs may help recreate conditions similar to those in natural lakes, potentially fostering more diverse and functional aquatic communities. As such, LiRs could represent a nature- based solution for enhancing ecological resilience in hydropower-regulated systems.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.162

Year: 2026