Sedimentary Heterogeneity Enhances the Diversity of Macrozoobenthos in Korean Tidal Flats

초록

A 6-year nationwide survey (2008-2013) was conducted in Korean tidal flats covering 890 stations to obtain a baseline for current status of coastal wetlands. We quantified the abundance, biomass, assemblage structure and distribution of macrobenthos at six different regions along the coasts of South Korea as follows: northern West Sea (nWS), middle West Sea (mWS), southern West Sea (sWS), western South Sea (wSS), eastern South Sea (eSS), and Jeju Island (JI). A Total of 727 macrobenthic species were reported from this study. Crustaceans dominated in terms of species richness (34% with 247 species) followed by polychaetes (30% with 218 species) and mollusks (26% with 187 species). Community structures were significantly different between regions according to an analysis of similarity (ANOSIM test). Species richness, abundance and biomass were all higher in the southern coasts except Jeju Island where tidal flats were limited spatially. Clustering analysis enabled the whole macrobenthic community to be distinguished into two groups of West Sea and South Sea. The similarity percentage (SIMPER) analysis for the best discriminating species detected the dominance of the polychaetes such as Mediomastus californiensis, Heteromatus filiformis, Lumbrineris longifolia, Glycinde gurjanovae, Tharyx spp. and also some micro-crustaceans such as Grandidierella japonica and Cyathura higoensis. The best correlation between the macrofaunal community and environmental variables in the BIOENV procedure was achieved by the combination of sorting coefficient and mean grain size of the sediment. Overall, these findings indicate that the sediment characters play an important role in structuring macrofaunal assemblages and in particular the sedimentary heterogeneity represented by a sorting coefficient may explain the high macrofaunal diversity in tidal flats of the southern coasts of Korea.