Biotic differentiation in headwater creeks after the massive introduction of non-native freshwater aquarium fish in the Paraíba do Sul River basin, Brazil

Abstract This study evaluated fish beta diversity in six headwater creeks located the area affected by largest ornamental aquaculture center implemented Minas Gerais State, southeastern Brazil. We sampled assemblages 2017 and 2018 to investigate changes assemblage structure (species richness diversity), comparing these data with historic species pool. recorded 60 species, of which 16 were native 44 non-native 19 translocated, 25 exotic. The exotics Poecilia reticulata, Xiphophorus maculatus, X. variatus, Danio rerio, Misgurnus anguillicaudatus most widely distributed creeks. Contamination Index showed that had high proportional contamination exotic (above 60%). Beta increased from historical contemporary periods all due introduction differential colonization pressure several translocated indicating biotic differentiation. Temperature number ponds main preditors change during period. In summary, we observed invaders have induced substantial communities under influence environmental filters. Our results support hipothesis is a driver biodiversity loss Neotropics.