Biodiversity and community structure of rivers from the arid, semi-arid and north-mediterranean zones of Chile

In this work the available information from scientific and technical studies is compiled and analyzed, to determine the taxonomic composition and trophic structure of river communities belonging to five hydrological basins of Chile, located within an arid-Mediterranean environmental gradient. The basins were: Loa, Huasco, Limari, Cachapoal y Mataquito. The four most important taxonomic groups were considered: fish, benthic macroinvertebrates, macrofites and benthic diatoms. The taxonomic and trophic structures of 10 communities from the studied basins were determined. The analyses indicated that: (a) each basin shows a characteristic taxonomic structure; (b) no patterns were found of increase or decrease in diversity along the arid-Mediterranean gradient, only finding a pattern along the upstream-downstream gradient within a system; (c) benthic macroinvertebrates shows a taxonomic particular and differentiable composition for the zones arid, semiarid and Mediterranean; (d) the taxonomic composition of each group was found to be significantly nested between rivers, and (e) five types of food webs were identified for the total of studied community systems, represented by functional groups and their feeding relationships. Future research should be oriented towards increasing the taxonomic resolution of the food webs and incorporate other relevant functional features.