Ecological and life history traits of Hemiodus orthonops in the invasion process: looking for clues at home

Abstract

The understanding of the environmental preferences and life history of a species in its native range provides insights for assessing its potential success in a novel area. Hemiodus orthonops is a migratory fish from the Paraguay and Middle Parana rivers that invaded the Upper Parana River through a fish pass, constructed in 2002. The invasion of this fish was analyzed based on habitat attributes and its life history in the native range and in the novel habitats. The native and novel habitats presented similar features. The population showed exponential growth in the years following the invasion, with relevant alterations in somatic growth, proportions of items in the diet, and in reproductive investment. The successful invasion appears to be related to similarities in water chemistry and habitat types between the native and novel range and the species' high dispersion ability. The species also showed earlier maturation and use of poor quality, but highly available feeding resources. Comparing life histories there was indication of a trade-off between investment in reproduction and somatic growth, with an increase in the latter in the novel habitats. In addition, the reproductive investment was more associated with offspring survival (oocyte size) than fecundity.