Ecological Analysis of Benthonic Foraminifera in Kagoshima Bay, South Kyûshû, Japan

• Main Author: ÔKI Kimihiko
• Format: Article in Journal/Newspaper
• Language: English
• Published: 鹿児島大学 1989
• Subjects: 457; Planktonic foraminifera
• Online Access: http://hdl.handle.net/10232/15702; https://ir.kagoshima-u.ac.jp/?action=repository_uri&item_id=5170; https://ir.kagoshima-u.ac.jp/?action=repository_action_common_download&item_id=5170&item_no=1&attribute_id=16&file_no=6

The assemblages of benthonic foraminifera in Kagoshima Bay, South Kyûshû, Japanwere quantitatively analyzed from a paleoecological point of view.Eighty-six of 146 bottom surface samples collected by gravity corer (PHLEGER's bottom sampler) were used for the ecological analysis of benthonic foraminifera. Livingspecimens were discriminated by the Rose Bengal staining method. One hundred andthirty-six samples were used for the mechanical analysis (EMERY settling-tube and pipette settling methods). Oceanographic observation on Kagoshima Bay has been carried out in alternate months from 1975 through 1979 by the staff of the Faculty of Fisheries, Kagoshima University. Those data were used for scrutinizing the environmental factors concerning the sea water characteristics in the area.The intensity and direction of the bottom currents were inferred from the results ofmechanical analyses of the bottom sediments and the oceanographic data. For all thespecies of which living specimens were recognized to occur, the ratio of the number of living specimens to the total (dead and living) number of individuals (L/Tl value) was calculated. Based on the L/Tl value, the relative rate of sedimentation at each sampling station was estimated. It has been pointed out that the L/Tl value well corresponds to the sedimentary environment inferred from the bottom current movement and the distribution of sediments, and it is a good index for sedimentary environment (ÔKI, 1986b, 1988). Taking the L/Tl value into consideration, the distribution patterns of number of individuals of planktonic foraminifera, of radiolaria and of benthonic foraminifera wereillustrated (Figs. 19, 20 and 24). Further, the ratio of planktonic foraminifera to the total foraminifera was calculated on each sample and was discussed in relation to water depth. The total (dead and living) benthonic foraminiferal specimens were divided into six groups through the cluster analysis (DAVIS, 1973) based on the percentage frequency data. The relationship between each clustered ...