Macrobenthic communities impacted by anthropogenic activities in an intertidal sand flat on the west coast (Yellow Sea) of Korea

Impacts on benthic macrofaunal communities by pollution and physical perturbation following seawall construction were assessed for an intertidal sand flat in Kyeonggi Bay, Korea near an industrialized harbour city. Despite the apparent input of a considerable amount of industrial effluents, no traces of heavy metal contamination were detected in either sediments or resident animals, probably owing to overall low percentages of mud. A seasonal cycle of silty sediment deposition and erosion also appears to play a role in alleviating metal accumulation in the sand flat. Recent seawall constructions, however, seem to have influenced the sedimentary environment. Sediment grain size became significantly coarser after seawall constructions and, associated with the grain size change, some shifts in dominance of abundant species were recorded. In addition, both total abundance and biomass significantly increased. In particular, abundance of the filter-feeding bivalve Mactra veneriformis increased ten times, seemingly benefiting from the coarser grain size. Changes in community structure were also reflected in k-dominance abundance curves.