Alpine Anthropogenic Waters Do Not Support the Natural Functional and Taxonomic composition of Dragon- and Damselfly Communities

Alpine regions host diverse habitats and rich biodiversity. Aquatic environments, crucial for many threatened species, are underrepresented in conservation. The creation of artificial water bodies impacts alpine aquatic ecosystems. While these novel habitats are proposed for biodiversity support, their suitability for alpine freshwater biota remains unclear. Dragonflies and damselflies, with their ectothermic physiology and semi-aquatic life cycle, are greatly constrained by both temperature and habitat features, thus potentially facing additive constraints in alpine artificial waters. We investigated Odonata communities on 41 anthropogenically altered and natural sites along a 2000 m elevational gradient in the European Alps, based on their abundance, diversity and traits associated with thermoregulation and life history as well as habitat preference. Thermoregulation differently affected dragonfly and damselfly communities, with an increase in body size and decrease in color lightness along decreasing temperature (i.e. increasing elevation) in dragonflies and an increase in color lightness in damselflies. Concurringly, damselfly abundances strongly decreased towards cold temperatures. In both suborders thermophily and habitat breadth decreased with decreasing temperature, but these trends were less pronounced in anthropogenic sites. Trait variation of dragonflies follows trends predicted by thermal melanism and Bergmann’s rule, while the absence of such trends in damselflies suggest limited thermoregulatory potential. The ecological distinctiveness of alpine anthropogenic sites can be linked to additive constraints of temperature and anthropogenic disturbance, thus preventing alpine species to utilize alpine artificial water bodies and challenging their potential for nature conservation in the face of global warming and biodiversity decline.