Quality of habitats in and around urban streams are important determinants of Odonata conservation

Urbanization is a key driver of freshwater biodiversity loss, yet the promotion of blue-green infrastructure in cities offers the potential for mitigation. The restoration of urban watercourses and their riparian areas could particularly benefit species inhabiting aquatic-terrestrial interfaces, such as dragonflies and damselflies (Insecta: Odonata). This study assessed Odonata diversity and assemblage composition across eight cities in southwest Germany, comparing stream sections in rural versus urban areas. Within cities, terrestrial and aquatic habitat quality was varied in a factorial design. Adult Odonata were recorded during section walks, and exuviae were sampled along riverbanks throughout 2024. In total, we observed adults of 16 species, with successful larval development confirmed by the presence of exuviae for seven species. Rural stream sections hosted 1.6 times more adult species than urban ones; however, urban sections with both high terrestrial and aquatic habitat quality supported species assemblages comparable to those of rural sections. Terrestrial habitat quality had a significant positive effect on both exuviae and adult species richness, with more than 1.5 times as many species present in high- compared to low-quality habitats. Furthermore, sections with high terrestrial habitat quality and those with high aquatic habitat quality each supported more than twice the number of adult individuals relative to their lower-quality counterparts. Our findings highlight the considerable potential of urban streams to support freshwater biodiversity. Effective conservation requires simultaneous improvement of both aquatic and terrestrial habitat quality, underscoring their joint importance in urban river restoration and planning. • Urban streams can support diverse Odonata, including endangered habitat specialists. • Rural stream sections support higher Odonata diversity than average urban sections. • Urban sections with high terrestrial and aquatic habitat quality match rural assemblages. • Oxygen concentration, pH, and canopy cover drive community composition across sites. • Integrated restoration of stream channel and riparian areas can boost urban stream biodiversity.