Impact of anthropogenic activities on changes of ichthyofauna in the middle and lower Xiang River

With the population increasing, fish communities, as important components in the river system, were inescapably impacted by human activities. To investigate these impacts, we characterized the fish community's composition by environmental DNA metabarcoding in the urban and suburban sites along Xiang River in central China. The results showed that 32 species were identified, and most species were from Cypriniform. The analysis indicated no significant differences in fish communities among the three urban areas. However, significant differences were observed between the bank solidified and non-solidified areas, which indicated that the channelization significantly influenced the biodiversity and abundances. An alien species, Clarias gariepinus, was discovered in all examined sites, and it was negatively associated with ten native species. Furthermore, human populations and acidification were also negatively related to diversity. Our findings clearly showed that the consequences of anthropogenic activities shaped ichthyofauna and caused biodiversity loss in the urban river.