Akio Akiyama *


The total area of tidal flats in Japan is 51,443ha in 1991. Forty percent of Japanese flats locates in the Ariake Sea (Kyushu Island).These are typical muddy flats,and important wintering grounds for migratory birds and habitats for rare species of fish such as Gobies Boleophthalmus pectinirostris and Taenioides rubicundus. The largest flat in Japan is 1,656ha shore flat in the Ariake Sea.

Most flats distribute sound sea such as Yatsushiro Sea(Kyushu I.), Tokyo Bay, MikawaBay, Ise Bay and Seto Inland Sea. After previous survey in 1978, 3,857ha of flats was disappeared. Approximately 35% of lost flats distributes in the Ariake sea. Beppu Bay(Kyushu I.), Tokyo Bay and Ise Bay have also lost large area of flat. Most lost flats were caused by development such as land filling.

It is shown from the result of sample survey that bio-diversity in flats is obviously high in shore flat.


* Department of Biology, Toho University.