Abstract: Marine biological productivity is a key factor regulating the export and burial of organic carbon, and its long-term
evolutionary patterns are of great significance for understanding the interaction between the carbon cycle and climate change. The South China Sea (SCS), as the largest marginal sea in the western Pacific, exerts profound impacts on regional carbon budgets and ecosystem structures through its productivity variations. Although productivity evolution in the SCS since the Last Glacial Maximum (LGM) has been extensively studied, results from different subregions exhibit remarkable spatial heterogeneity. These discrepancies may arise from the heterogeneous response of different regions to climate change, and/or inherent ambiguity of productivity proxies coupled with their susceptibility to potential post-depositional diagenetic alterations. In this study, we systematically reviewed the applicability and implication of commonly used productivity proxies in the SCS, including fluxes of total organic carbon, C37 alkenones and opal, as well as benthic foraminiferal assemblages. Based on a comprehensive evaluation of these proxies, we compared and analyzed the productivity evolution patterns of the SCS during the LGM and the Holocene. The results show that the gross productivity in the northern, southeastern part of the SCS and areas surrounding the Sunda Slope was generally higher during the LGM and lower in the Holocene. In contrast, the southwestern to central-southern parts of the SCS exhibited lower productivity during the LGM compared to the Holocene. The pattern of productivity evolution is likely primarily influenced by local hydrological processes regulated by the combined effects of monsoon dynamics and sea level changes. This study not only offers crucial insights into the coupling mechanisms between monsoon and productivity on glacial-interglacial timescales, but also provides a scientific basis for predicting responses of marginal sea carbon cycle under future global warming scenarios. 

Key words: South China Sea, biological productivity, Last Glacial Maximum, regional discrepancies