Responses and influencing factors of benthic macroinvertebrate recovery in restored subtropical urban rivers

Urban streams in many regions of the world are subject to water environment and ecological degradation, and the efficacy of conventional remediation strategies remains uncertain. This study evaluated the initial ecological recovery in rehabilitated urban streams by analyzing the response of benthic macroinvertebrates community and water quality. The effects of hard embankment engineering were quantified using an Index of Biological Integrity (IBI), which was derived from five core indicators: number of taxa, Shannon-Wiener index, Tubificidae%, tolerant% and collectors%. Data were collected from 29 sampling sites across 11 treated urban channels in Guangzhou City. As impervious surface area increased, sensitive species declined or vanished, while pollution-tolerant species like Oligochaeta and Chironomidae became dominant. Macroinvertebrate diversity and functional feeding groups significantly decreased, leading to “very poor” and “poor” health statuses. Key water parameters affecting benthic species diversity included dissolved oxygen (DO), chemical oxygen demand (COD_Mn), total phosphorus (TP), depth, and flow velocity. The Shannon-Weiner index and functional feeding group for macroinvertebrates show seasonal consistency in disturbance zones (P < 0.05). However, Benthic Index of Biological Integrity (B-IBI) assessment results vary seasonally, correlating significantly with disturbance intensity, indicating benthic communities' sensitivity to habitat stressors. Water replenishment strategies mitigate early urbanization impacts, highlighting their role in boosting urban stream resilience and offering new insights for ecological rehabilitation and global urban river management.