Depth distribution of benthic foraminifera in the middle and deeper sublittoral to uppermost bathyal zones northwest of Okinawa, Japan

Distribution of dominant species of porcelaneous foraminifera is related to depth in the sublittoral and uppermost bathyal around Okinawa, Japan. Depth is a composite factor that influences physical factors, i.e., temperature, salinity, substrate caused by hydrodynamics and illumination. Depth distribution of optimally preserved porcelaneous tests demonstrate optima in the middle sublittoral, deeper sublittoral and uppermost bathyal zones. Optimal depth distribution of the tests in the middle and deeper sublittoral zones is related to dependence on either coarse sand, medium sand or no dependence on specific substrate type. Optimal depth distribution of the tests in the uppermost bathyal zone is related to dependence on fine and very fine sand. Porcelaneous tests have shown partial agreement between the depth distribution and dependence on substrate type. Life position of the porcelanous foraminifera is influenced by test dominance in percentages of silt and clay. Dominance in the high percentages of silt and clay is reflected in infaunal life position. Dominance in the low percentages of silt and clay is reflected on epifaunal life position. Dominance in medium percentages or no dominance reflects on either epifaunal or infaunal life position. Test dominance in percentages of silt and clay is related to its dependence on substrate type.