Performance of the Cumulative Biotic Index (CBI) and other biotic indices in assessing ecological health of the Upper Citarum River, Indonesia

Abstract

The macroinvertebrate multimetric concept is widely employed to assess the ecological condition of freshwater ecosystems subjected to anthropogenic pressures. In this study, the Cumulative Biotic Index (CBI) was evaluated as a region-specific biocriteria-based tool to assess the ecological health of the Upper Citarum River, which has been heavily impacted by socioeconomic development. The objectives were to (1) assess the diversity and evenness of benthic macroinvertebrate communities, (2) identify key environmental factors influencing community structure, and (3) evaluate the sensitivity of the CBI in comparison with other established biological indices. Field surveys were conducted between September 2022 and August 2023 across 15 stations, applying rapid assessment protocols to measure water quality, habitat conditions, and benthic macroinvertebrate identifications. A total of 124 macroinvertebrate genera were identified, with diversity and evenness categorized as moderate to low (H’ = 2.6–0.3 nits) and stability ranging from medium to low (J = 0.75–0.27), indicating a decline at disturbed sites. Multivariate analyses revealed that organic enrichment (total nitrogen, total phosphorus), sedimentation (turbidity, percent embeddedness), and habitat disturbance (habitat index) were the primary factors shaping community composition. Among seven tested biological indices, the CBI demonstrated the highest sensitivity in distinguishing ecological gradients, underscoring its potential as a robust biomonitoring tool for evaluating restoration efforts in river ecosystems, particularly in Indonesia and other tropical rivers with similar conditions.