Ecological Health Assessment of the Vam Co River System, Vietnam: Insights from Benthic Macroinvertebrates and Environmental Changes

This study investigated the relationships between benthic macroinvertebrates and environmental variables in the Vam Co River system in southern Vietnam. Field surveys were conducted four times from May to November 2023 to evaluate seasonal variations in macroinvertebrate diversity and water quality. The river, characterized by moderate pollution levels, elevated nutrient concentrations, and substrates mainly composed of fine and coarse sand, significantly influences the distribution and abundance of benthic macroinvertebrates. A total of 32 species were identified, with bivalves and crustaceans being the most prevalent groups during the sampling period. Benthic macroinvertebrate densities ranged from 28 to 167 individuals per square meter, reflecting habitat quality linked to the substrate type. Biodiversity, assessed using the Shannon–Wiener index (H’), varied from 1.51 to 2.94, whereas the average tolerance score per individual (ATSPI) ranged from 37 to 51, indicating moderate-to-good ecological health. Species richness was positively associated with pH, total suspended solids (TSS), and dissolved oxygen (DO), suggesting that these factors support diverse communities. Conversely, ATSPI scores, which indicate pollution tolerance, were positively correlated with biochemical oxygen demand (BOD5), total nitrogen (T_N), and total phosphorus (T_P) and negatively correlated with pH, total suspended solids (TSS), and DO. These findings demonstrate the importance of benthic macroinvertebrates as bioindicators of river health and underscore the need for ongoing integrated monitoring and adaptive management to promote the sustainable conservation of the Vam Co River system.