Seasonal variations in planktonic foraminiferal flux and the chemical properties of their shells in the southern South China Sea

• Published in: Science China. Earth sciences Vol. 53; no. 8; pp. 1176 - 1187
• Main Authors: Wan, Sui, Jian, ZhiMin, Cheng, XinRong, Qiao, PeiJun, Wang, RuJian
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science China Press 01.08.2010; Springer Nature B.V
• Subjects: Biochemistry; Carbon isotopes; Chemical properties; Chlorophyll; Earth and Environmental Science; Earth Sciences; Fluctuations; Geochemistry; Globigerina bulloides; Globigerinita glutinata; Globigerinoides ruber; Globigerinoides sacculifer; Marine; Marine biology; Monsoons; Neogloboquadrina dutertrei; Organic carbon; Oxygen isotopes; Plankton; Pulleniatina obliquiloculata; Research Paper; Sea surface temperature; Seasonal variations; Seasons; Seawater; Sediments; Temperature gradients; Water depth; Water temperature; South China Sea; ISEW, South China Sea; sediment trap; planktonic foraminifera; seasonal change; oxygen and carbon isotope; East Asian monsoon; southern South China Sea; Mg/Ca ratio
• ISSN: 1674-7313; 1869-1897
• DOI: 10.1007/s11430-010-4039-3

Results from sediment trap experiments conducted in the southern South China Sea from May 2004 to March 2006 revealed significant monsoon-induced seasonal variations in flux and shell geochemistry of planktonic foraminifera. The total and species-specific fluxes showed bimodal pattern, such as those of Globigerinoides ruber, Globigerinoides sacculifer, Neogloboquadrina dutertrei, Globigerinita glutinata , and Globigerina bulloides . Their high values occurred in the prevailing periods of the northeast and southwest monsoons, and the low ones appeared between the monsoons. Pulleniatina obliquiloculata had high flux rates mainly during northeast monsoon, with exceptional appearance in August 2004. These fluxes changed largely in accord with those of total particle matter and organic carbon, following chlorophyll concentration and wind force. It is inferred that the biogenic particle fluxes are controlled essentially by primary productivity under the influence of East Asian monsoon in the southern SCS. Shell stable oxygen isotope and Mg/Ca data correspond with seasonal variation of sea surface temperature. Shell δ 18 O values are affected primarily by sea water temperature, and the δ 18 O changes of different-depth dwelling species indicate upper sea water temperature gradient. Besides, the low carbon isotope values occurred in the periods of East Asian monsoon in general, whereas the high ones between the monsoons. The pattern is in contrary to chlorophyll concentration change, which indicates that the variation of the carbon isotope could probably reflect the change of sea surface productivity.