@article{oai:niigata-u.repo.nii.ac.jp:00006851, author = {Kurihara, Toshiyuki and Shimotani, Toyokazu and Matsuoka, Atsushi}, journal = {Science reports of Niigata University. (Geology), Science reports of Niigata University. (Geology)}, month = {Mar}, note = {The profiles of water properties and vertical distribution of radiolarian faunas are documented from the surface to subsurface water shallower than 100m deep in the Sea of Japan, off Tassha, Sado City, Sado Island, Niigata Prefecture, central Japan. The temperature from 64m deep to the surface ranges from ca. 12.0°C to 18.0°C. Based on temperature gradient, the water mass can be subdivided into three layers. The surface layer shallower than 21m has a high temperature gradient (2.0°C/10m). This profile indicates that the water mass is in the intermediate condition between the winter to spring and summer seasons. The faunal compositions for three different depth intervals can be summarized as follows: (1) the fauna collected from ca. 90-63m deep is characterized by the abundant occurrences of Cyrtidosphaera reticulata and plagiacanthid and lophophaenid nassellarians, associated with Tetrapyle octacantha, Didymocyrtis tetrathalamus tetrathalamus, and Larcopyle butschlii,(2) the faunas collected from ca. 63-36m and 36-0m deep are similar to those of the deeper fauna but their compositions are quite different; T. octacantha and D. t. tetrathalamus are relatively abundant instead of C. reticulata. For C. reticulata and L. butschlii, there is a close correlation between lowering temperature in the vertical profile and increasing numbers of individuals. This may be caused by their temperature tolerance ranges. In addition, species preferring warm water such as D. t. tetrathalamus comprise a large percentage of the shallower fauna than the deeper. Taken the temperature profile and faunal data together, we conclude that the faunal transition off Tassha is mediated by the influx of warm water dwellers of the Tsushima Warm Current into the surface layer of the water column during spring to summer.}, pages = {31--46}, title = {Water temperature, salinity, algal-chlorophyll profiles and radiolarian fauna in the surface and subsurface waters in early June, off Tassha, Sado Island, central Japan}, volume = {21}, year = {2006} }