日本近海における現生底生有孔虫の深度分布 : 古水深尺度の確立に向けて  [in Japanese] Bathymetric distribution of the Recent benthic foraminifers around Japan : As a contribution to the new paleobathymetric scale  [in Japanese]

The faunal distribution pattern of modern benthic foraminifers is delineated with the aim of establishing a precise paleobathymetric scale. In view of modern oceanography, seas around the Japanese Islands are divided into three regions: the Kuroshio and Oyashio regions in the Pacific off southwest and off northeast Japan, respectively, and the Japan Sea region. In each region, bathymetric zonations are proposed based on available data about the distribution of modern thanatocoenoses. Each of the eight bathymetric zones in both the Kuroshio and Oyashio regions, and the six zones in the Japan Sea corresponds well to a particular water mass. The upper and lower boundaries of each bathymetric zone differ in water depth among the regions, and even with any of the regions. The upper limits of the total distribution of single species are even more variable across the zonal boundary. On the contrary, the depth of diverging-downward frequency distribution of each species is restricted with a given bathymetric zone. Consequently, the term 'the shallow bathymetric zone (SBZ)' is proposed for a bathymetric zone that includes a considerable range of the upper depth limit of distribution of the species concerned because of their variations in water depth. On the basis of compiled bathymetric distribution data, the SBZ is estimated for every benthic species in the two regions in the Pacific and the open-sea and coastal areas in the Japan sea region, separately.