Características reprodutivas de peixes invasores no rio Paranapanema, bacia do alto rio Paraná, sul do Brasil | Reproductive characteristics of invasive fishes in the Paranapanema River, Upper Paraná River basin, southern Brazil

Studies on reproductive biology can provide explanations for successful colonization of new areas, as biological characteristics associated with invasive species may confer advantage on invasion. We aimed at evaluating variations of reproductive characteristics of invasive fishes in lagoons and free-from-dam rivers. Populations of Serrasalmusmarginatus, Loricariichthysplatymetopon, Ossancoraeigenmanni, Auchenipterusosteomystax and Trachelyopterusgaleatus were studied in lentic (Lagoons 1 and 2) and lotic habitats (Pirapozinho and Anhumas rivers) during dry and wet seasons. Females predominated in most populations (χ², α < 0.05). Females of L.platymetopon and T.galeatus presented higher gonadosomatic index during the wet season in the Anhumas River and Lagoon 2, respectively (Mann-Whitney test, α < 0.05). Populations of S.marginatus, L.platymetopon, O.eigenmanni, and T.galeatus showed very intense reproductive activity in Lagoon 1. Trachelyopterusgaleatus showed very intense reproductive activity in the two lagoons and the Pirapozinho River. While some species exhibit high reproductive investment, regardless of habitat type (T.galeatus), others may present variations (S.marginatus and L.platymetopon). Females with higher sex ratios, high reproductive investment, parental care, internal fertilization and split spawning may be features that favor establishment in the recipient area. Serrasalmusmarginatus and L.platymetopon have Equilibrium/Seasonal and Equilibrium life history strategy, respectively, while A.osteomystax e T.galeatus have Seasonal strategy. Due to the presence of individuals that are dispersed, survive and reproduce in different habitat types, these species have an extensive area of occurrence and have successfully invaded the Upper Paraná River basin. Therefore, actions are needed to control populations and minimize their impacts.