Elevated nutrients and surface chlorophyll-α associated with natural methane seeps in the Haima cold seep area of the Qiongdongnan Basin, northern South China Sea

Pengfei Di; Niu Li; Linying Chen; Junxi Feng; Duofu Chen

doi:10.1016/j.marpolbul.2023.114873

Elevated nutrients and surface chlorophyll-α associated with natural methane seeps in the Haima cold seep area of the Qiongdongnan Basin, northern South China Sea

Mar Pollut Bull. 2023 Jun:191:114873. doi: 10.1016/j.marpolbul.2023.114873. Epub 2023 Apr 7.

Authors

Pengfei Di¹, Niu Li², Linying Chen³, Junxi Feng⁴, Duofu Chen³

Affiliations

¹ Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Sanya Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511481, China. Electronic address: pfd@scsio.ac.cn.
² Key Laboratory of Ocean and Marginal Sea Geology, South China Sea Institute of Oceanology, Sanya Institute of Oceanology, Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China; Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511481, China.
³ Shanghai Engineering Research Center of Hadal Science and Technology, College of Marine Sciences, Shanghai Ocean University, Shanghai 201306, China.
⁴ MNR Key Laboratory of Marine Mineral Resources, Guangzhou Marine Geological Survey, Ministry of Natural Resources, Guangzhou, Guangdong 510075, China.

PMID: 37031642
DOI: 10.1016/j.marpolbul.2023.114873

Abstract

Cold seeps are a significant source of methane to the ocean. However, nutrients and Chl-α in the euphotic layer overlying cold seeps have been poorly studied. Variations in Chl-α, nutrients, environmental parameters, and CH₄ concentrations in the Haima cold seeps were analyzed. Results show that the overlying water exhibits a typical low nutrient and low Chl-α marine environment. Phosphate and Chl-α were significantly elevated, and the average SCM in cold seeps was much higher than that in control stations. Spearman correlation analysis indicated Chl-α in cold seep was positively correlated with salinity and negatively with nutrient and CH₄ concentrations. It implied that the CH₄ concentrations may promote the increase of Chl-α, and may be linked to CH₄ plumes, bringing cold, nutrient-rich waters to the thermocline. However, due to the CH₄ plumes hardly to track, more sampling is needed to determine the effects on Chl-α and phytoplankton in the euphotic layer.

Keywords: CH(4) concentration; Chl-α; Haima cold seeps; Nutrients; Qiongdongnan Basin.

MeSH terms

China
Chlorophyll*
Methane* / analysis
Phytoplankton
Water / analysis

Substances

Chlorophyll
Methane
Water