Efeitos da macrófita invasora Hydrilla verticillata sobre as diversidades alfa e beta de Chironomidae.

Abstract

Invasion of species can influence both alpha and beta diversity of aquatic communities. Macrophyte Hydrilla verticillata (L.F.) Royle is one of the main submerged invasive species on the planet and can cause changes in the associated communities. In this study we investigated the effects of invasive H. verticillata on alpha and beta diversity of Chironomidae community, comparing to native correlative Egeria najas Planch. For this purpose, we conducted an experiment in situ with native and invasive plants being held in the same water physical and chemical conditions, and at the same time of colonization by invertebrates, which have been identified and functionally characterized. To test differences in taxonomic and functional alpha diversity we applied paired t tests. The differences in the beta diversity were tested by multivariate dispersion (PERMDISP). We found larger functional richness of Chironomidae in association with invasive specie, probably in consequence of the difference in species composition observed between the macrophytes, because organisms of different species may have different functional characteristics in the communities. However invasive species caused a taxonomic homogenization in the chironomid community. Our result may be related to the evolutionary history between the native plant and these invertebrates. It is likely that there has been a selection of chironomid adult between the two plants in a micro-scale, and most chironomid species are probably more adapted to deposit their eggs and settle in native species than in invasive. Studies of interactions between the chironomid community and the microbiota or other organisms associated with native and invasive plants are needed to know if the effects observed here affect other trophic levels.