Abundance of invasive peacock bass increases with water residence time of reservoirs in southeastern Brazil

Neotropical freshwater ecosystems are experiencing a great expansion in the number of invasive species, which is especially alarming since this region harbours 30% of the world’s fish biodiversity with high levels of endemism. We aimed to evaluate the main predictors of peacock basses (Cichla spp.) abundance outside their native range, which are the Amazon and Tocantins-Araguaia river basins. We used multivariate ordination techniques and multimodel inference to analyse peacock basses abundance in twelve reservoirs of the Paraíba do Sul river basin, southeastern Brazil. Interestingly, reservoirs at higher (southernmost) latitudes, located in more populated areas, had higher water temperature and lower turbidity, due to increased water residence time, and these three variables were also positively correlated with abundance of this warm-water invasive fish. Habitat structure was less important in explaining peacock basses abundance, which was not significantly related to biotic factors (fish species richness and time since peacock basses introduction). We hypothesize that the observed effects of reservoir management on limnological features and peacock bass abundance, particularly water residence time (as a mediator of temperature and turbidity), may apply to other Neotropical basins and could influence the impact of this invader.