Abstract
The marine algal communities along the coast of Izura, Kita-Ibaraki City, Ibaraki Prefecture, were studied from January 1961 to January 1962 and also from March 1967 to August 1969. As the result, the Hixikia fusiforme-Eisenia bicyclis association was bound to be distributed dominantly along the exposed shore of the coast. The Hizikia fusiforme-Eisenia bicyclis association is a typical community of Japan on the open sea coast of the Pacific Ocean. This fact was already found by TANIGUCHI (1965) on the coasts of Fukushima Prefecture, Boso, Miura, Izu, Atsumi, Shima and Kii Peninsulas, and the eastern and western coasts of Kyushu, etc. This association consists of two distinct belts : the Hizikia fusiforme upper belt and the Eisenia bicyclis lower belt. In the community of a sheltered shore, the Hizikia fusiforme-Eisenia bicyclis association is not separated distinctly into two belts and many other algal species are found in it. The difference found in the local communities is caused by wave action. The writer has newly observed that Gigartina intermedia and Sargassum sagamianum oum in the Hizikia fusiforme-Eisenia bicyclis association, and that the Ishige okamurai-and Ishige sinicola communities are not found along this coast.
