Leucorrhinia pectoralis can coexist with fish (Odonata: Libellulidae)

The Palaearctic libellulid Leucorrhinia pectoralis is generally considered to be a species inhabiting fish-free water bodies. Yet, a long-term monitoring study of 38 water bodies in NE Germany resulted in 16 species of fish being recorded in reproductive habitats of L. pectoralis, with Rutilus rutilus and Carassius carassius as the most numerous and widespread fish species. Only 14 water bodies were certainly or probably without fish. The seasonal numbers of exuviae of L. pectoralis at the water bodies ranged between 0.1 and 136 per 10 m of bank section. The abundance of L. pectoralis was higher in fish-free water bodies (an average of 28.0 exuviae/10 m) than in fish-inhabited waters (1.7 exuviae/10 m). The emergence success of L. pectoralis depended on the density and species composition of the fish. If only one non-piscivorous fish species (Carassius carassius, Tinca tinca) was present at low density, the abundance of exuviae averaged 6.5/10 m. In water bodies containing a multispecies fish fauna that included piscivorous species, combined with high fish density only 0.7 exuviae/10 m were found on average. At localities where the fish fauna was dominated by Perca fluviatilis virtually no emergence of L. pectoralis occurred.