Seasonal dinoflagellate cyst production and terrestrial palynomorph deposition in the East Asian Monsoon influenced South China Sea: A sediment trap study from the Southwest Taiwan waters

Zhen Li, Vera Pospelova, Hui Ling Lin, Lejun Liu, Bing Song, Wenping Gong

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9 Scopus citations

Abstract

The South China Sea (SCS), influenced by the tropical East Asian Monsoon (EAM), experiences winter monsoon and summer monsoon shifts in near-surface wind, air temperature, sea-surface temperature, salinity, primary productivity, and other oceanographic conditions. To understand how monsoon seasons influence palynological dynamics and which palynological index could be a reliable indicator of winter or summer monsoons, we studied palynological records of sediment trap samples collected in March–April (winter monsoon season) and July–August (summer monsoon season). Fluxes and assemblages of terrestrial pollen and spores, as well as marine dinoflagellate cysts, were investigated using sediment traps in the southwest Taiwan waters of the SCS. The pollen and spores of 109 taxa and dinoflagellate cysts of 53 taxa were identified in 24 sediment trap samples that were collected at 3-day intervals. The average abundance of Pinus pollen was notably higher in March–April at ~ 40%, which was double that in July–August. This trend was associated with transport by the northwest wind in March–April when Pinus pollen are produced by the coniferous vegetation in the South China and Taiwan Island. The pollen abundances of Chenopodiaceae/Amaranthaceae and Compositae seemed to be greatly reduced in July–August, with an opposite pattern observed for Poaceae, Artemisia, Cyperaceae, Typha, and fern spores. Fluvial transport is likely the controlling factor since river runoff intensifies in summer. High relative abundances and fluxes of Poaceae pollen are not indicators of summer monsoons but related to cultivated activities. Dinoflagellate cyst assemblages were dominated by cysts produced by heterotrophic taxa, especially Brigantedinium spp. at 68–91%. Proportionally higher increases than those of cysts produced by autotrophic dinoflagellates resulted in lower heterotrophic to autotrophic ratios in July–August. The highest total cyst fluxes occurred in late July of ~ 20,000 cysts m-2 d-1 together with the highest fluxes of autotrophic Operculodinium centrocarpum, Spiniferites spp., and Lingulodinium hemicystum. The increased fluxes of almost all dinoflagellate cyst taxa during July–August were related to the decreased sea-surface salinity (SSS) due to the greater river water inputs and nutrients.

Original languageEnglish (US)
Pages (from-to)117-139
Number of pages23
JournalReview of Palaeobotany and Palynology
Volume257
DOIs
StatePublished - Oct 2018
Externally publishedYes

Bibliographical note

Funding Information:
The Natural Sciences and Engineering Research Council of Canada (NSERC) CGS D3 fellowship ( CGSD3-475098-2015 ) and Montalbano scholarship provided partial funding for this research to Z. Li. This work was also funded by NSERC through a Discovery grant ( RGPIN/6388-2015 ) to V. Pospelova. She is the Hanse-Wissenschaftskolleg (HWK) senior research fellow in marine and climate research at the Institute for Advanced Study (Germany). H.-L. Lin was supported by the Ministry of Science and Technology Grants of Taiwan ( NSC 98–3114–E–006– 014 and NSC 99–2611–M–110–006 ). L. Liu was partially supported by the National Program on Global Change and Air-Sea Interaction ( GASI-GEOGE-05 ) from the State Oceanography Administration of China in this work, and B. Song and W. Gong were supported by Chinese Natural Science Foundation Projects of No. 41506103 and No. 51761135021 , respectively.

Funding Information:
The Natural Sciences and Engineering Research Council of Canada (NSERC) CGS D3 fellowship (CGSD3-475098-2015) and Montalbano scholarship provided partial funding for this research to Z. Li. This work was also funded by NSERC through a Discovery grant (RGPIN/6388-2015) to V. Pospelova. She is the Hanse-Wissenschaftskolleg (HWK) senior research fellow in marine and climate research at the Institute for Advanced Study (Germany). H.-L. Lin was supported by the Ministry of Science and Technology Grants of Taiwan (NSC 98–3114–E–006– 014 and NSC 99–2611–M–110–006). L. Liu was partially supported by the National Program on Global Change and Air-Sea Interaction (GASI-GEOGE-05) from the State Oceanography Administration of China in this work, and B. Song and W. Gong were supported by Chinese Natural Science Foundation Projects of No. 41506103 and No. 51761135021, respectively.

Keywords

  • Dinoflagellate cysts
  • East Asian monsoon
  • Palynology
  • Seasonal change
  • Sediment trap
  • South China Sea

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