Can the introduction of non-native fish induce variation in life-history traits of a native species in a neotropical lake?

Abstract

Top predator fish, such as peacock bass (Cichla kelberi) and red-bellied piranha (Pygocentrus nattereri), were introduced in the lacustrine system of the Rio Doce basin and these introductions are associated with loss of aquatic biodiversity. The present work aims to investigate the life-history traits of a native species, thraira (Hoplias malabaricus), in the context of the pressures caused by the introduction of top predator fishes. Two lakes were selected in a conservation unit Doce River State Park (PERD), namely, Lake Carioca, where P. nattereri and C. kelberi were introduced, and Lake Gambazinho, where H. malabaricus occurs in the absence of introduced fish. In total, 146 specimens of H. malabaricus were caught, including 95 in Lake Gambazinho and 51 in Lake Carioca. Significant differences were found in the length–weight relationship (LWR) in the diet, the reproductive period, the vitellogenic follicle size, and the gonadosomatic index (GSI). In the lake with introduced species, thrairas showed allometric growth, a less diversified diet, longer duration of the reproductive period, and high GSI values compared with the control lake. The results indicated that the life-history traits of thrairas can be influenced by the environmental modification caused by the introduction of non-native peacock bass and red-bellied piranha.