The invasive macrophyteHydrilla verticillatacauses taxonomic and functional homogenization of associated Chironomidae community

摘要

Exotic species have invaded freshwater ecosystems, causing biodiversity loss of associated communities. We investigated the influence of the invasive macrophyteHydrilla verticillataon taxonomic and functional richness, and on taxonomic and functional beta diversity of associated Chironomidae community, comparing this macrophyte with the structurally similar native macrophyte,Egeria najas. We conducted a field experiment where the native and invasive plants were kept side-by-side and colonized by invertebrates. We used accumulation curves to test if richness differed between macrophytes. We used multivariate dispersion to investigate whether taxonomic and functional composition differed between both macrophytes and to test if beta diversity was higher among individuals of the native than among individuals of the invasive macrophytes. We measured beta diversity values as an average distance of the compositions to the centroid in a multidimensional space (taxonomic and functional) given by a Principal Coordinates Analysis. We found similar taxonomic richness and similar taxonomic and functional Chironomidae composition between macrophytes. However, functional richness as well as taxonomic and functional beta diversity of Chironomidae were higher among the native than among the invasive macrophytes. Thus, althoughH. verticillatadid not cause changes neither in Chironomidae taxonomic richness nor on taxonomic and functional composition, its spread may drive the simplification of species and functional traits of associated Chironomidae communities.