Environmental heterogeneity associated with boat activity shapes bacteria and microeukaryotic communities with discrepant response patterns.

With the development of global tourism, tourist boats, a significant form of anthropogenic disturbance, are having an increasingly serious impact on the structure and function of aquatic ecosystems. In this study, the effects of different intensities of tourist boat activities on the microbial communities of West lake, were investigated by high-throughput sequencing. The results showed significant differences in the composition of bacterioplankton and microeukaryotic communities between the high-intensity boat activity (HIBA) area and low-intensity boat activity (LIBA) area. Variation partitioning analysis showed that environmental factors contributed the most to microbial community variation, and the effect of boat activities on microbial communities mainly occurred through coupling with environmental factors. The contribution of boat activity to microbial community changes occupies the second place, the first being environmental factors. Co-occurrence network analyses showed that microbial communities in the HIBA area had more nodes and edges, higher connectivity and lower modularity than in the LIBA area, suggesting a more complex and stable network. Networks of associations between potential keystone taxa and environmental factors reveal the way in which boat activity affects microbial communities. The bacterial community responded strongly to environmental factors associated with boat activities, whereas the microeukaryotic community was more likely to be regulated by interspecific interactions. This also suggests that when faced with disturbances from the boat activity, microeukaryotes might exert a stronger direct resistance effect compared to bacterioplankton. These findings imply that bacterioplankton and microeukaryotes demonstrate distinct response patterns in the presence of disturbance caused by boat activity. Our research expand our understanding of the effects of boat activities on aquatic ecosystems and provide further insights into the assessment of anthropogenic disturbances in aquatic ecosystems.