Assessing the effect of environmental factors and land use changes on benthic macroinvertebrate communities in stream ecosystems
Jong-Won Lee, Sang‐Woo Lee, Se-Rin Park
Abstract
The ecological integrity of stream communities is shaped by the complex interplay of multiple environmental factors. This study employed a Bayesian Network (BN) approach based on Structural Equation Modeling (SEM) to evaluate the relative influence of environmental factors on the condition of benthic macroinvertebrates in streams. The analysis focused on 24 impaired streams within the Hangang River Basin in South Korea, using monitoring data collected from 2018 to 2022. Eleven input variables related to watershed land use (WLU), water quality (WQ), and physical habitat quality (PHQ) were incorporated into the model. The population density ratio of benthic macroinvertebrates and the benthic macroinvertebrate index were used as endpoints, serving as dependent variables. Sensitivity analysis identified WQ as the key factor influencing benthic macroinvertebrate communities in urban and agricultural watersheds, whereas PHQ was the most significant factor in forest watersheds. Scenario analyses further demonstrated that changes in PHQ and WQ could significantly alter the likelihood of benthic macroinvertebrate health degradation, depending on WLU changes. Notably, the probability of benthic macroinvertebrate impairment due to WQ degradation was higher in streams with good PHQ than in those with poor PHQ, suggesting that streams with better physical conditions are more vulnerable to the negative effects of poor WQ. This study provides a comprehensive understanding of how freshwater organisms respond to complex environmental dynamics within streams and watersheds. The findings underscore the importance of integrating both direct and indirect environmental impacts into watershed and stream management strategies to preserve the biological integrity of aquatic communities.