[Diversity and Ecological Network Characteristics of Planktonic Bacterial Communities in Raohe River]

Planktonic bacteria play a vital role in the material cycling and energy flow of river ecosystems. However， little is known about the diversity and co-existence network relationship of riverine planktonic bacteria under multiple stressors. This study investigated the impact of nutrients， heavy metals， and antibiotics on the planktonic bacterial diversity and co-existence relationship in Raohe River， the classic river entering Poyang Lake， as well as its two tributaries， Changjiang and Le'an Rivers. The results showed that planktonic bacterial community structure varied significantly among the three river sections， and the alpha diversity of planktonic bacteria in Le'an River was significantly lower than that in Changjiang and the lake entry segment. The dominant planktonic bacterial phyla were Proteobacteria， Bacteroidetes， and Actinobacteria in Raohe River. The co-occurrence network analysis revealed that the network complexity and relative abundance of key species of planktonic bacteria in the lake entry segment were higher than those in Changjiang and Le'an River， indicating that the co-existence relationship of planktonic bacteria were stronger in the lake entry segment. A variance partitioning analysis indicated that nutrients and heavy metals were the main driving factors for the diversity and co-existence relationship of planktonic bacteria. The research results contribute to understanding the characteristics of riverine planktonic bacteria influenced by multiple stressors and provide a scientific basis for predicting and managing the ecological health of the river.