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Eating the competitor: a mechanism of invasion

Pereira, Larissa Strictar, Agostinho, Angelo Antonio, Gomes, Luiz Carlos
Hydrobiologia 2015 v.746 no.1 pp. 223-231
Hoplias, diet, fish, indigenous species, ingestion, invasive species, predation, predators, watersheds
The success of predators in species invasion will depend on their interactions with their own predators and competitors. The present study examined whether the predation of piscivorous fish among other piscivorous fish could be an active mechanism in species invasion. The diet of eleven piscivorous fish found in the upper ParanĂ¡ River basin was analyzed during eight years. Seven of the fish species were native to the river basin, and four were invasive species. The diet composition of the studied species did not differ from each other, and a high value of niche overlap was found among invasive species with native species. Invasive species consumed higher amounts of piscivorous species, mainly Hoplias sp. 1 and C. kelberi. Salminus brasiliensis was the only native species with high values of predation over piscivorous fish. There were no significant differences between the consumption of piscivorous fish and their abundance. Overall, the consumption of piscivorous fish by invasive species can act as a mechanism for their success and maintenance in a new environment. Piscivorous invaders radically change the composition of their new environment more than other trophic levels; therefore, we recommend special care with the introduction of piscivores.