Stream restorations with meanders increase dragonfly and damselfly diversity and abundance, including an endangered species

•Many streams were artificially linearized for human usage, but with probable negative effect on biodiversity.•Two streams were restored with meanders and diggings allowing water to run again.•On both restored streams, diversity and abundance of Odonata (dragonflies & damselflies) significantly increased.•The endangered southern damselfly (Coenagrion mercurial) colonized both streams after restorations.