Can the Ecological Quality of Several Bays in South Korea Be Accurately Assessed Using Multiple Benthic Biotic Indices?

Bays are extensively impacted by human activities, and an accurate assessment of ecological quality is crucial for the environmental management and protection of bays. Most studies indicate that evaluating the ecological quality of bays using a single index presents challenges. In our study, we used five benthic biotic indices and a composite index to assess the ecological quality of three bays in South Korea. Our results revealed disparities in the ecological quality status assessment using five benthic biotic indices. The composite index performed better than the other benthic biotic indices in a principal coordinate analysis. Significant differences were observed between the values classifying stations as having an acceptable or unacceptable final ecological quality in terms of species indices (except for the Pielou’s evenness index) and the abundance of opportunist species (<i>p</i> < 0.05). Consequently, we advocate for using a composite index to assess the ecological quality of the bays of the West Sea of South Korea. Furthermore, our study provides valuable information for marine ecological management and policy formulation in Korea and offers recommendations for using the composite index in future research.