Intermediate disturbance hypothesis explains eutrophication and biodiversity pattern in a boreal river basin, China

Eutrophication is a common phenomenon in aquatic ecosystems caused by human disturbance and is regarded as one of the major threats to biodiversity in rivers throughout the world. However, no consistent pattern explains the relationship between eutrophication and biodiversity in rivers. In the present work, we explored fieldwork in connection to the influence of eutrophication on biodiversity in nine streams in a boreal river ecosystem in China. We aimed to test the intermediate disturbance hypothesis (IDH) in our model, which predicts that biodiversity reaches its maximum at intermediate disturbance. We used total phosphorus (TP) as a direct indicator of eutrophication and divided TP concentration into five levels of eutrophication, which represented anthropogenic disturbance of varied intensity. The results obtained from periphyton, macroinvertebrate, and fish assemblages showed that species richness was higher at intermediate eutrophication levels, and the pattern was not impacted by other factors. Our findings may provide important insights into the influence of anthropogenic disturbance on biodiversity in stream ecosystems.

Automated summary

Eutrophication caused by human disturbance is a common phenomenon in aquatic ecosystems and poses a major threat to river biodiversity worldwide. However, there is no consistent pattern explaining the relationship between eutrophication and biodiversity in rivers. In this study, we conducted fieldwork in a boreal river ecosystem in China and found that species richness was highest at intermediate eutrophication levels, unaffected by other factors. These findings provide important insights into the impact of anthropogenic disturbance on biodiversity in stream ecosystems.