Ecological interruption on food web dynamics by eutrophic water discharge from the world’s longest dike at Saemangeum, Yellow Sea

•Confirmed the world's longest man-made dike impact on tidal flat food web dynamics.•Revealed eutrophic water discharge impact on the nutritional and microalgal distribution.•Characterized the greater MPB contribution to benthos by eutrophic water input.•Identified distinct discharge water impact on diet utilization of filter/deposit feeders.