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Could native predators help to control invasive fishes? Microcosm experiments with the Neotropical characid, Brycon orbignyanus

Santos, A.F.G.N., Santos, L.N., García-Berthou, E., Hayashi, C.
Ecology of freshwater fish 2009 v.18 no.3 pp. 491-499
Astyanax altiparanae, Brycon orbignyanus, Cichla, Ictalurus punctatus, Oreochromis niloticus, Prochilodus lineatus, fish, introduced species, invasive species, juveniles, microhabitats, predation, predators, tropics, watersheds
The potential of the native characid, Brycon orbignyanus, to help to control some invasive fish species currently present in the Paraná River basin was addressed through microcosm experiments. Juveniles of three invasive (Cichla piquiti, Oreochromis niloticus and Ictalurus punctatus) and two native (Astyanax altiparanae and Prochilodus lineatus) fish species were offered as prey to B. orbignyanus in 300-l aquarium trials with three habitat complexity treatments (0%, 50% and 100% structure). Prey survival was much more variable among species (I. punctatus < C. piquiti < O. niloticus~P. lineatus~A. altiparanae) than through time, and B. orbignyanus predation was clearly mediated by habitat complexity, with lower prey survival in low-complexity treatments. The lower survival observed for C. piquiti could be partially explained by its less active behaviour and its preference for a surface microhabitat and less structured areas. Prey size also affected predation rates, as for the three less consumed species the largest individuals were significantly preyed on. Our results suggest that preserving and restoring the populations of B. orbignyanus might help to control some fish species introduced to the Paraná River basin, particularly I. punctatus and C. piquiti.