Odonates (Odonata) as indicators of the natural potential of sand mine ponds (Central Europe): environmental drivers and implications for biodiversity conservation

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Odonates (dragonflies and damselflies) are well-recognized indicators of freshwater ecosystems; therefore, they were used to describe the natural potential of man-made habitats, i.e. sand ponds, in terms of species, ecological patterns of the occurrence of both larval and adult assemblages, as well as environmental drivers. In total, 52 species (41 spp. as larvae and 51 spp. as imagines) were recorded in 10 sand-mine ponds in eastern Poland in 2018. The odonatofauna of the individual water body was highly diverse, and the species represented different ecological groups (eurytopes, spp. associated with astatic water bodies, tyrphophiles, limnophiles, rheophiles). The arrangement of the sites on NMDS diagrams for larvae and adults was consistent: it was ruled by the size of the pond and the close/open area gradient. CCA analyses revealed that both developmental stages were driven by very similar patterns of the groups of environmental variables: the sand pond structure and vegetation were the most important, whereas sediments and water properties had the weakest impact. We also analysed “special concern” species, as they reflect the natural values of the studied habitat type and can serve as indicators for conservation activities related to the management and protection of these habitats. The fact that 29% of all species identified belonged to this category confirms the high potential of anthropogenic aquatic environments in maintaining freshwater biodiversity in dynamically changing aquatic ecosystems. By managing some habitat features within sand mines and their ponds (e.g. both aquatic and riparian plants, their composition and structure, shoreline, shading, fish pressure), it is possible to create favourable conditions not only for aquatic insects but also for the entire biota. Thus, it is possible to maintain and promote high local biodiversity within these still underestimated man-made habitats.