Evaluating Ecological Quality in the Subtidal Zone off Jindo Island, South Korea Using Multiple Benthic Indices

Context. Rapid coastal development and aquaculture expansion along the South Korean coast have intensified anthropogenic pressure on benthic ecosystems, highlighting the need for reliable ecological assessment tools. Aims. This study assessed the ecological quality status (EcoQS) of the subtidal zone off Jindo Island, South Korea. Methods. Five benthic indices, namely the AZTI Marine Biotic Index (AMBI), BENTIX, benthic polychaeta amphipoda index (BPA), Benthic Pollution Index (BPI), multivariate AMBI (M-AMBI), and a composite index were applied to evaluate EcoQS across three survey years. Multivariate analyses were performed to identify the influence of environmental variables on community structure. Key results. Ninety-eight macrobenthic species were recorded. Most stations exhibited acceptable EcoQS according to AMBI, BENTIX, BPI, and M-AMBI, whereas BPA classified many as moderate or poor, underscoring the limitations of single-taxon approaches. Lead (Pb) concentration in seawater was identified as a key driver of macrobenthic community variation, particularly in years with enhanced terrestrial runoff. Conclusions. Although Pb levels were below national thresholds, their ecological effects were evident, indicating subtle but measurable community responses.