Multiple anthropogenic pressures and local environmental gradients in ponds governing the taxonomic and functional diversity of epiphytic macroinvertebrates

Anthropogenic activities alter community composition, diversity and functioning of macroinvertebrate communities in freshwater ecosystems. Especially threatened are pond ecosystems, given their small size, low protection, and typically high connection to adjacent agricultural lands and urban areas. Most of the existing research, however, focuses on benthic macroinvertebrates while the evidence for epiphytic macroinvertebrates is strongly limited. Here we tested the effects of different anthropogenic activities on abundance, taxonomic and functional diversity, and composition of epiphytic macroinvertebrates in ponds along the gradients of local environmental factors. We found that all types of anthropogenic activities had negative impact on abundance, and on both taxonomic and functional diversity, and altered taxonomic and functional composition of epiphytic macroinvertebrates. Among the local environmental factors, macrophyte growth forms governed diversity and community composition, having positive effects on the taxonomic diversity, but allowing only a narrow spectrum of macroinvertebrate functional traits to persist on a single growth form of macrophytes. Fish predation was an important determinant of functional diversity of epiphytic macroinvertebrates. Our findings suggest that management strategies aimed to maintain high levels of biodiversity in ponds should be directed towards reducing the level of anthropogenic pressure, while ensuring the presence of distinct macrophyte growth forms in ponds.