High-resolution reconstructions of Holocene Sea-surface conditions from dinoflagellate cyst assemblages in the northern South China Sea

Type Article
Date 2021-08
Language English
Author(s) Li Zhen1, 2, Pospelova Vera2, 3, Liu Lejun4, Francois Roger1, Wu Yongsheng5, Mertens KennethORCID6, Saito Yoshiki7, 8, Zhou Rui9, Song Bing10, Xie Xin11
Affiliation(s) 1 : Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 329 West Mall, Vancouver, British Columbia V6T 1Z4, Canada
2 : School of Earth and Ocean Sciences, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2, Canada
3 : Department of Earth and Environmental Sciences, University of Minnesota, 116 Church St SE, Minneapolis, MN 55455, USA
4 : First Institute of Oceanography, MNR, 6 Xianxialing Road, Qingdao 266061, China
5 : Fisheries and Oceans Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia B2Y 4A2, Canada
6 : Ifremer, LER BO, Station de Biologie Marine, Place de la Croix, BP40537, F-29185 Concarneau Cedex, France
7 : Estuary Research Center, Shimane University, Nishikawatsu-cho 1060, Matsue 690-8504, Japan
8 : Geological Survey of Japan, AIST, Tsukuba 305-8567, Japan
9 : State Key Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai, China
10 : Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, 73 East Beijing Road, Nanjing 210008, China
11 : State Key Laboratory of Marine Geology, Tongji University, 1239 Siping Road, Shanghai 20092, China
Source Marine Geology (0025-3227) (Elsevier BV), 2021-08 , Vol. 438 , P. 106528 (20p.)
DOI 10.1016/j.margeo.2021.106528
Keyword(s) Paleoceanography, Sea-surface temperature, Sea-surface salinity, Marine primary productivity, Dinoflagellate cysts, The South China Sea, Holocene, Anthropogenic impacts
Abstract

A high-resolution dinoflagellate cyst analysis on a sediment core GLW1D from the northern South China Sea (SCS) was performed to reconstruct paleoceanographic conditions over the last 12,500 years through qualitative, semi-quantitative, and quantitative methods. A modern dataset with 398 reference sites in the northern Pacific was assembled and used to identify the relationship between dinoflagellate cyst assemblages and sea-surface temperature (SST), sea-surface salinity (SSS) and primary productivity (PP). Modern analog technique (MAT) was applied to offer first dinoflagellate-cyst-based quantitative estimates of Holocene sea-surface conditions in the western North Pacific. The downcore reconstructions show that SST, SSS and PP were predominantly controlled by the changes in coastal and oceanic currents due to the changes of sea level and monsoon systems. Our results indicate that SST increased while SSS and PP decreased from 12,500 to ~6800 cal yr BP, reaching the maximum SST and the minimum SSS and PP during ~6800–5000 cal yr BP, and followed by a slight decline in SST with minor increases in SSS and PP. The three intervals correspond to the regional onshore sea-level stages of rising, stabilization in a highstand and slight drop, respectively. The Kuroshio Current strongly influenced the core site before ~9900 cal yr BP, reflected by the highest abundances of oceanic Impagidinium spp. and high reconstructed SSS values. This can be explained by a lack of water input from the East China Sea before the opening of the Taiwan Strait. The warmest period, from ~6800 cal yr BP to ~5500 cal yr BP, is recorded by the highest Dapsilidinium pastielsii abundances. Two short-term high-PP events of ~2700–2400 cal yr BP and ~1000–600 cal yr BP, which were characterized by opposite climatic conditions, coincided with two notable societal (dynasty) collapses of China. Enhanced anthropogenic activities since the Late Bronze Age most likely partially affected the high PP through influencing river inputs to the northern SCS.

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Li Zhen, Pospelova Vera, Liu Lejun, Francois Roger, Wu Yongsheng, Mertens Kenneth, Saito Yoshiki, Zhou Rui, Song Bing, Xie Xin (2021). High-resolution reconstructions of Holocene Sea-surface conditions from dinoflagellate cyst assemblages in the northern South China Sea. Marine Geology, 438, 106528 (20p.). Publisher's official version : https://doi.org/10.1016/j.margeo.2021.106528 , Open Access version : https://archimer.ifremer.fr/doc/00697/80948/