Application of functional feeding groups of macroinvertebrates in highly urbanized streams

Urbanization is an inevitable process accompanying the economic development. However, the rapid urbanization process is posing a threat to aquatic communities and causing disruptions to river ecosystems. In highly urbanized river ecosystems, the mechanisms of human activities on the functional feeding groups (FFGs) of macroinvertebrates remain unclear, hindering the restoration of river ecosystems. This study focuses on an urban stream called the Yangmei River in Guangzhou and investigates environmental factors and macroinvertebrates in August and November 2022 and February and May 2023. Variance analysis, principal component analysis, and hierarchical cluster analysis were employed to research the temporal and spatial characteristics of FFGs. Redundancy analysis was used to explore the environmental factors influencing FFGs. Finally, ecosystem attributes were calculated based on FFG data and ratios. The results indicate that gathering-collectors dominate in the Yangmei River, leading to a transition toward a heterotrophic river system. Simultaneously, the damaged material transportation function, weakened riparian function, and poor habitat stability all reveal the fact of partial functional degradation of the Yangmei River. This study provides valuable insights into the overall functionality of the Yangmei River and contributes theoretical support for the application of FFG methods in the ecological assessment of highly urbanized rivers.