Effects of fish predators and abiotic factors on dragonfly community structure

We compared the community structure of odonates (Odonata) in 13 waters in northern Sweden, which differed with respect to fish presence and abiotic factors. Richness and abundance of odonates were estimated by collecting exuviae during the whole emergence season of 1999. Redundancy analysis revealed that fish presence influenced the community composition of the odonate larvae. While species richness per sample was not affected by the presence of fish, total abundance of odonates was higher in waters without fish. In waters with fish, Aeschna juncea and Leucorrhinia dubia showed lower abundances, whereas Erythromma najas and Cordulia aenea showed higher abundances. The abundances of Coenagrion hastulatum, Libellula quadrimaculata, and Leucorrhinia rubicunda did not differ between waters with and without fish. Of the six abiotic factors analyzed only water acidity was associated with odonate community structure.