Does one community shape the other? Dragonflies and fish in Swedish lakes

Abstract

Abstract. 1. Freshwater communities are often structured by predation. In permanent lentic freshwater habitats dragonfly larvae are major predators which, in return, suffer predation by fish. Antipredator traits vary between the dragonfly species, and the dragonfly communities are therefore shaped by the presence of fish. But fish communities vary, and as different fish species affect dragonflies in different ways, the species composition of the fish community may affect the composition of the dragonfly community.2. We sampled dragonfly larvae in 24 lakes with a known fish stock in south‐western Sweden, and explored the impact of fish as well as vegetation structure on dragonfly communities by means of multivariate analyses.3. We found that the presence of four fish species affected the community structure of dragonflies. The impact strength depended mainly on the abundance ofPerca fluviatilis, with which most dragonfly species were negatively correlated. Many dragonfly species were also positively correlated with the occurrence of at least one fish species, which may reflect similar habitat requirements or imply indirect positive effects of these fish species.4. Of the 24 recorded dragonfly species, four did not occur in lakes dominated byP. fluviatilis, whereas only one species was lacking in lakes dominated byRutilus rutilus. The dragonfly species diversity was higher inR. rutiluslakes than inP. fluviatilislakes.5. Our results suggest that the fish species composition is a major determinant of the dragonfly community, which in turn will influence the lower trophic levels.