Impact of upwelling on phytoplankton blooms and hypoxia along the Chinese coast in the East China Sea

Chung-Chi Chen; Fuh-Kwo Shiah; Gwo-Ching Gong; Tzong-Yueh Chen

doi:10.1016/j.marpolbul.2021.112288

Impact of upwelling on phytoplankton blooms and hypoxia along the Chinese coast in the East China Sea

Mar Pollut Bull. 2021 Jun:167:112288. doi: 10.1016/j.marpolbul.2021.112288. Epub 2021 Apr 7.

Authors

Chung-Chi Chen¹, Fuh-Kwo Shiah², Gwo-Ching Gong³, Tzong-Yueh Chen⁴

Affiliations

¹ Department of Life Science, National Taiwan Normal University, 88, Sec. 4, Ting-Chou Rd., Taipei 11677, Taiwan. Electronic address: ccchen@ntnu.edu.tw.
² Research Center for Environment Changes, Academia Sinica, NanKang, Taipei 11529, Taiwan; Institute of Marine Environment and Ecology, National Taiwan Ocean University, Keelung 20224, Taiwan.
³ Institute of Marine Environment and Ecology, National Taiwan Ocean University, Keelung 20224, Taiwan; Center of Excellence for the Oceans, National Taiwan Ocean University, Keelung 20224, Taiwan.
⁴ Institute of Marine Environment and Ecology, National Taiwan Ocean University, Keelung 20224, Taiwan.

PMID: 33836334
DOI: 10.1016/j.marpolbul.2021.112288

Abstract

This study evaluates the rarely observed phenomenon of the simultaneous occurrences of phytoplankton blooms, hypoxia, and upwelling along the Zhejiang coast in the East China Sea. Results show that the upwelling uplifted bottom water to 5-10 m below the surface. In the upwelling region, phytoplankton blooms (Chl a = 10.9 μg L^-1) occurred and hypoxia or low-oxygen appeared below the surface water. High concentrations of nitrate and phosphate were regenerated in the hypoxic regions, corresponding with mean values (± SD) of 16.9 (± 1.5) and 0.90 (± 0.14) μM, respectively. The upwelling expanded the region of hypoxic water, which nearly reached the surface, thereby increasing the threat to marine life. In addition to fluvial nutrients, the upwelling of water with high nutrient levels, especially phosphates, can enhance phytoplankton blooms. The results suggest that hypoxia can become more severe due to further decomposition of bloom-derived organic matter after blooms crash.

Keywords: East China Sea; Hypoxia; Nutrient regeneration; Phytoplankton blooms; Upwelling; Yangtze River.

MeSH terms

China
Humans
Hypoxia
Phosphates* / analysis
Phytoplankton*
Seasons

Substances

Phosphates