Chironomidae functional traits in Atlantic Forest streams: spatial and temporal patterns

Abstract

We used Chironomidae functional attributes to assess how spatial and temporal scales influence assemblage structure. We collected Chironomidae larvae in 10 streams from southern Brazil over 5 years and measured land use, limnological variables, and rainfall. We use substrate and habitat preference as ecological attributes and feeding habits and tube construction as biological attributes. We performed a between-class correspondence analysis using spatial and temporal scales. In years with greater rainfall and turbidity and lower water temperature, the predominant functional characteristics were preferred for lotic environment and leaf substrate. On the spatial scale, in streams that showed more exposed soil, the predominant functional characteristics were lentic habitat and muddy substrate. For streams with more vegetation, pasture, and electrical conductivity, the ecological trait was leaf substrate. The functional structure of assemblage responds to both scales only for ecological attributes. On the spatial scale, we observed that land use was the main predictor, whereas on the temporal scale, rainfall was the most important predictor. We emphasize that extreme climatological phenomena can potentialize the effects of environmental variables, which shows the importance of the time scale for environmental quality.