Abstract
The bottom sediments and benthic foraminiferal assemblages in Kagoshima Bay, southern Kyushu, Japan, were quantitatively analyzed from sedimentological and paleoecological viewpoints. The submarine topography and the distribution of bottom sediments in the bay's mouth and central areas suggest that the predominant currents move northwards along the coast of the Osumi Peninsula and southwards along the coast of the Satsuma Peninsula, with a postulated counterclockwise gyre in the central area. Longshore currents flowing southwards along the Satsuma Peninsula are diverted by an extensive area of reclaimed land at Kiire Town, and this influences the distribution of the bottom sediments offshore. The vertical distribution of grain size in sediment cores taken at two stations off the reclaimed land supports the idea mentioned above. Bottom sediments off Ibusuki City were swept away during the period from 1938 to 1972. This erosion seems to have been caused mainly by the excavation of iron sand and the construction of piers. Prior to the installation of further engineering works in nearshore areas, detailed hydrological and sedimentological investigations are needed in order to appraise their likely impact on the surrounding sea bottom and the benthic commuinity.
