Changes in ground beetle (Coleoptera, Carabidae) assemblages along an industrial pollution gradient in the Southern...

Industrial pollution can negatively affect ground beetles individuals and populations. At the same time, effects at the community level remain poorly understood and published data are inconsistent. The study analyzes changes in ground beetle assemblages (abundance, species composition, and diversity) along the pollution gradient caused by emissions from the Karabash Copper Smelter (KCS, Southern Urals, Russia). Sampling was conducted in 2009 and 2014 at 10 birch forest sites with different contaminant exposure and ecosystem disturbance. The abundance and diversity of ground beetles decreased in the heavily polluted area and the relationship with the distance to KCS was non-linear. Segmented regression provided the best fit to the data. The breakpoints after which the parameters decreased sharply differed among indices and were recorded at distances of 9-11 km to KCS for species richness, 7-10 km for diversity and 4-5 km for abundance. Heavy pollution affected species composition and ecological traits of dominant species. Spatial variations in all indices were consistent across years with differing weather conditions. Ground beetle larvae were recorded throughout the entire gradient, with the exception of the extremely disturbed industrial barren. The absence of larvae at the barren suggests that local reproduction is impossible; all individuals likely migrated from nearby areas.