Freshwater Fish Biodiversity in a Large Mediterranean Basin (Guadalquivir River, S Spain): Patterns, Threats, Status and Conservation

The Guadalquivir River Basin is one of the largest in Iberian Peninsula and has a remarkable freshwater biodiversity. Although many studies on hydrological regimes or water quality have been conducted this basin biodiversity fish, as well their distribution conservation status, never globally addressed other basins. In context, we synthesized information fish using field procedures bibliographic search. Fish patterns at different spatial scales general environmental conditions were analyzed status community. We documented presence 40 species (20 native 20 exotic) during 20th century until today. However, only captured 18 sampling, with prevalence for any less than 23% (except Luciobarbus sclateri). highest richness was found mid reaches, while lower reaches had very low diversity values. Around 50% are threatened; according to IUCN, several declining an alarming rate others probably extinct and/or current unknown. Human disturbances last few decades caused serious changes consequently status. Hydrological alterations, intensive agriculture introduced principal reasons Guadalquivir’s ichthyofauna imperilment. Our study indicates urgent real need identify important areas guarantee minimum over long term, effective strategies recovery where it still possible.