Analysis of Marine Ecology During the Last Warming Period of Bolling-Allerod Based on the Abundance and Diversity of Planktonic Foraminifera in the Makassar Strait Maharani Rachmawati Purnomo (a), Marfasran Hendrizan (b), Rima Rachmayani (c), Niken Sitalaksmi Siagian (a), Muhammad Abyan Nauli Harahap (a), Oktavira Dwi Demia Larasati (a)
a) Study Program of Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Jl. Ganesha, No. 10, Bandung 40132, West Java, Indonesia
*rachmaharanii[at]gmail.com
b) Paleoclimate and Paleoenvironment Research Group, Research Center for Climate and Atmosphere, Research Organization for Earth Sciences and Maritime, National Research and Innovation Agency Republic of Indonesia (BRIN), Jl. Sangkuriang, Bandung 40135, West Java, Indonesia
c) Research Group of Environmental and Applied Oceanography, Faculty of Earth Sciences and Technology, Bandung Institute of Technology, Jl. Ganesha, No. 10, Bandung 40132, West Java, Indonesia
Abstract
Foraminifera is one of the proxies used to reconstruct paleo-global climate change, including the condition of marine ecosystems. This study focuses on the last Bolling-Allerod (B/A) warming period (13,102-14,920 bp). Reconstruction of paleo-ecology in this study uses analysis of the abundance and diversity of planktonic foraminifera. Furthermore, the relationship between marine ecology was analyzed to reconstruct thermocline depth as seen from the comparison of thermocline dwellers with mixed layer dwellers, climate condition and Indonesian Throughflow (ITF) intensity in the Makassar Strait.
Observations on 5 sediment samples, 10 genera and 17 species of planktonic foraminifera were obtained. The most dominant species in the study area are Globigerinita glutinata and Globigerinoides ruber, species that inhabit mixed layers and water paleo-productivity tends to be low. In this period, the thermocline dwellers value was 39.76-47.31% (average 42.62%), indicating a deeper thermocline layer^s depth and strengthen Indonesian Throughflow (ITF). The change in depth of thermocline (DOT) that occurred at sediment core location (TR1926-B) are thought to be associated with the shift in the ITCZ, the dominance of the western monsoon, and a La Nina-like phenomenon around Indonesia.
The results of foraminifera assemblage at sediment core (TR1926-B) were influenced by paleo-ecology changes. At the end of B/A period, there was an increase in mixed layer dwellers. Cooling conditions were found in the middle of the B/A period, characterized by a decrease in the abundance of Globigerinita glutinata, Pulleniatina obliquiloculata, and Trilobatus trilobus. A decrease in the abundance of Globigerina bulloides and small amount of Globototalia sp characterized oligotrophic paleo-ecology conditions.
