Nile tilapia (Oreochromis niloticus) invasions disrupt the functional patterns of fish community in a large subtropical river in China

Although non-native species can modify ecosystem function, their effects in southern China have not been investigated, despite their ecological importance. This study assessed how Nile tilapia Oreochromis niloticus (L.) invasions impact the functional patterns of fish communities in the large subtropical Pearl River by analysing the relationships between invasion and body size over a 9-year period. The relative abundance of Nile tilapia increased significantly over time. In particular, the established Nile tilapia significantly undermined the relative densities and the body size of the native fishes. Importantly, this study provided empirical evidence that functional indices (such as body size) are more sensitive when evaluating the effects of non-native species on a community than richness. Understanding processes such as those should be the basis of controlling alien fish species and fisheries management in the Pearl River.