Long-term study of reservoir cascade in south-eastern Brazil reveals spatio-temporal gradient in fish assemblages

摘要: In reservoir cascades, effects on fish assemblages are expected to strengthen over time and transfer from one an adjacent one. To test this, fish-assemblage data 23 years of monitoring in the Araguari cascade system, upper Parana River basin, were analysed. The results showed a clear reduction richness native migratory species increase non-native species, following formation. Migratory was higher reservoirs that presented habitats similar lotic stretches or tributaries upstream impounded area. There tendency for decline increase, downstream direction. Fish became increasingly dissimilar as more distant each other (longitudinal gradient) dominated by small medium-sized species. Alongside longitudinal position, area, age presence herbivorous found be important predictors variation structure. Results present study help clarify potential accumulated impacts cascades diversity, which must carefully considered river-basin inventories hydropower plants, reinforce importance long-term monitoring, considering lateral dimensions basin.