Assessment of Benthic Ecological Quality Status in the Subtidal Zone of Northern Jeju Island, South Korea, During Summer Based on Macrobenthos

Background: Jeju Island is a world-renowned tourist destination. However, with the increasing intensity of anthropogenic activities, the coastal marine environment of Jeju Island has been negatively affected. Methods and Results: Our study used five benthic indices to assess the ecological quality of the subtidal zone in northern Jeju Island. Our analysis indicated that apart from the benthic polychaetes amphipods index (BPA), other benthic indices assessed the ecological quality of the subtidal zone in northern Jeju Island as high or good. Distance-based redundancy analysis (dbRDA) indicated that pH and salinity primarily influenced macrobenthic communities in 2011 and 2012. According to the Spearman rank correlation analysis, the multivariate AZTI marine biotic Index (M-AMBI) showed stronger correlations with environmental data than other benthic indices. Conclusions: Overall, the averages of the five benthic indices suggested that the benthic ecological quality of the subtidal zone in the northern part of Jeju Island was high or good. Although immediate marine environmental management is not required, long-term monitoring remains essential. M-AMBI outperformed other benthic indices; however, we recommend using multiple benthic indices to assess the benthic ecological quality of Jeju Island due to the complexity of marine ecosystems. Effective support has been provided by our study for the marine environmental conservation along the coast of Jeju Island.