Environmental related variation in growth and life-history traits of non-native sailfin catfishes (Pterygoplichthys spp.) across river basins of South China

Plasticity in growth and life-history traits is an important attribute of non-native (NN) fishes, facilitating their adaptation to novel environments. Few studies have investigated geographical variations in multiple biological traits and the factors affecting the variations. In this study, variations in multiple biological traits of NN sailfin catfishes Pterygoplichthys spp. were investigated in the main river basins of the Guangdong and Hainan provinces of South China. The impacts of environmental factors on the biological traits were analysed using general linear modeling and an informationtheoretic approach. Among-basin differences in population growth was observed, with richness of competitor fishes negatively affecting growth, maturity and reproductive traits – this suggests biotic resistance was mediated by competition with native fishes. These traits were positively affected by total phosphorus concentration, which is indicative of bottom-up effects, mediated by inorganic nutrients, potentially playing an important role in the invasion success of NN fish. In population level, a bet-hedging strategy was observed in sailfin catfishes under unfavourable environment conditions (e.g. Nangdujiang), whereas a “master-of-some” strategy was found under favourable conditions (e.g. Pearl River Delta and Western Basin). The results suggested that plasticity in multiple biological traits of sailfin catfishes is an important strategy to overcome changing environmental conditions in different rivers, and habitat-specific variations across river basins would reflect trade-offs amongst traits at the population level. Therefore, habitat-specific management measures, adapted to the invaded ecosystem’s features and the life-history strategy of the NN species, could provide an effective means to control invasive species.