The Sone tidal flat in Kitakyushu city has a dry flat of about 517ha during ebb tides. It is one of the nicest spots for the wild bird observation through the four seasons. It is also famous as the breeding ground of Horseshoe crab (Tachypleus tridentatus). Although large-scale landfills have been recently constructed around the Sone tidal flat, number of Horseshoe crab breeding pairs laying eggs have been increasing. The aim of this study is to identify changes in wave environments due to the large-scale landfills through a numerical wave model and to understand physical habitat environments of Horseshoe crab larvas through field studies.
A drastic decrease in the wave intensity due to the large-scale landfills is confirmed and may be one of the reasons for increase in number of the breeding pairs. Also, basic physical characteristics of Horseshoe crab larva's habitat environments are identified and discussed.
