Macroinvertebrates functional feeding groups (FFGs) of forested streams draining urban catchments in the Niger Delta: identifying and classifying vulnerable and tolerant FFGs

This study aims to assess the vulnerability and tolerance levels of macroinvertebrate functional feeding groups (FFGs) in forested streams draining urban areas in the Niger Delta. It contributes to our understanding of how human activities affect freshwater ecosystems. Between 2008 and 2012, we conducted monthly measurements of physicochemical variables and collected macroinvertebrates. We categorised sampling sites into three groups based on disturbance levels: least impacted sites (LIS), moderately impacted sites (MIS), and heavily impacted sites (HIS). Multivariate (RLQ) analysis was used to visualise associations among physicochemical variables across the sampled sites, revealing distinct relationships between certain FFGs and different sites. The RLQ model we constructed showed that grazers and collector-filterers were predominantly observed in LIS, suggesting their vulnerability to environmental stressors. Conversely, predators and shredders were more prevalent in impacted sites (MIS and HIS), indicating their tolerance to disturbances such as elevated nitrate levels and higher water temperatures. The fourth corner graph highlighted differing responses of FFGs to physicochemical variables, with predators showing positive correlations with several factors but no significant association with phosphate levels. Overall, these findings showed the importance of considering the responses of different FFGs to environmental variables in assessing the health and integrity of aquatic ecosystems.