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

• Published in: Marine pollution bulletin Vol. 191; p. 114873
• Main Authors: Di, Pengfei, Li, Niu, Chen, Linying, Feng, Junxi, Chen, Duofu
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-06-2023
• Subjects: CH4 concentration; China; Chl-α; Chlorophyll; Haima cold seeps; Methane - analysis; Nutrients; Phytoplankton; Qiongdongnan Basin; Water - analysis; China; Qiongdongnan Basin; CH4 concentration; Nutrients; Chl-α; Haima cold seeps; CH concentration
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2023.114873

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.
•The Haima cold seeps in Qiongdongnan Basin, SCS exhibited a typical low-nutrients low-chlorophyll marine environment.•The phosphate, nitrate and Chl α increased significantly in cold seep stations, but no significant different in abundance.•Temparatue, dissolved O2 content and phosphates were major factors leading to the change of Chl α, while dissolved CH4 may another factor control change of Chl α in cold seep station.