Ecological changes of intertidal fauna by coastal reclamation in Song-do tidal flat, Incheon, Korea

초록

Changes to the structure of benthic communities in Song-do tidal flat, Incheon, Korea were determined by comparing results of a survey of 41 stations in 1994 and 1997 with a survey of 11 stations in 2014. The stations located at the upper and middle intertidal were reclaimed so that the stations of the lower intertidal along this seaward transect, each 100m apart, were studied. Macrobenthic sampling was conducted using a can corer (20 15 30) in August 2014 and the other data in 1994 and 1997 were from the Benthic Ecology Laboratory, Inha University, Korea. Before the coastal reclamation, tidal flat consists mainly of fine-grained clastic detritus and this low-energy macrotidal regime results in conspicuous, broadly intergradational zonations of sediment textures and benthic mnacrofauna across an intertidal expanse more than 4km wide (Frey et al., 1987). The tripart zonation was very clear and the macrofaunal biodiversity become higher toward the seaward flat: (1) Brachyuran Zone, a landward sandy mud flat characterized ecologically by the crabs Ilyoplax pingi and Macrophthalmus japonicus, (2) Molluscan Zone, a mid-flat of sandy clayey silt typified mainly by the bivalve Solen strictus and the gastropod Umbonium thomasi, and (3) Holothurian Zone, a seaward flat of sandy silt to silty sand characterized primarily by the holothurian Protankyra bidentata. After reclamation, the tidal flat of lower part only remained approximately 1km long (11 stations). As a result, the macrobenthic biodiversity remains somewhat similar compared to the pre-reclamation period, but the abundance and biomass remarkably reduced. A total of 114 macrobenthic fauna was found with a mean density of 751 inds./m2 and biomass 92. 18g WWt./m2. Here, we compare and discuss the community parameters, zonation pattern, and the dominant species between the pre- and post-reclamation period in the Song-do tidal flat, Incheon, Korea