The Influence of Environmental Variables on Distribution of Macrobenthic Community in Salt Marsh Vegetation in Donggeomdo, Ganghwa on the West Coast of Korea

This study examined the relationship between macrobenthic distribution patterns and environmental factors in salt marsh vegetation in Donggeomdo, Ganghwa on the west coast of Korea. Nine stations were fixed on a transect across the salt marsh vegetation, and field sampling was carried out monthly from July 1997 to June 1998. A total of 38 species of macrobenthos were recorded: each of faunal groups, 13 (34.2%) Arthropoda, 12 (31.6%) Polychaeta, 8 (21.1%) Mollusca, and 5 (13.2%) others. The mean density was 2,659 individuals/㎡, with a mean biomass of 178.6 gWWt/㎡. Mollusca dominated in terms of abundance and biomass, with a mean density of 2,172 individuals/㎡ (81.7%) and a mean biomass of 131.9 gWWt/㎡ (73.9%). The number of species decreased in winter (January−February), while mean density increased in the spring (May−June). The biomass was relatively in Summer and Fall (July−November), than any other season. The number of species was high in pure stands of Suaeda japonica in the lower salt marsh vegetation, and the mean density and biomass were high in mixed halophyte communities in the middle salt marsh vegetation. Two Mollusca, the bivalve Glauconome chinensis and gastropod Assiminea lutea, were dominant. The densities of these two species were high in mixed halophyte communities in the middle salt marsh vegetation. Non-metric multi-dimensional scaling (nMDS) showed that the study area could be divided into four groups corresponding to the vertical distribution of tidal levels and halophytes. Spearman’s rank correlation revealed that the distribution patterns and community structure of macrobenthos were related to environment variables such as salinity of the substrates, exposure time, and grain size compositions of the sediment in the salt marsh vegetation. Particularly, the distribution and density of some dominant species showed differences along the vertical distributions of halophytes.