delta C-13 and fatty acid composition of mesopelagic fishes in the South China Sea and their influence factors

• Published in: Chemistry and Ecology
• Main Authors: Wang, Fuqiang, Wu, Ying, Cui, Ying, Chen, Zuozhi, Li, Zhongyi, Zhang, Jun, Zheng, Shan
• Format: Report
• Language: English
• Published: TAYLOR & FRANCIS LTD 2019
• Subjects: Mesopelagic fishes; lipids; delta C-13; fatty acids; temperature; South China Sea; Biochemistry & Molecular Biology; Environmental Sciences & Ecology; Ecology; Environmental Sciences; POTENTIAL DIETARY INFLUENCE; SCOTIA SEA; STABLE-ISOTOPES; FEEDING ECOLOGY; CARBON; PHYTOPLANKTON; COASTAL; EXTRACTION; NUTRITION; Scotia Sea; Southern Ocean
• Online Access: http://ir.qdio.ac.cn/handle/337002/162335; https://doi.org/10.1080/02757540.2019.1651844

Study of the ecology of mesopelagic fishes is central for assessing the active biological pump in the ocean, especially in the mesopelagic layers. The use of delta C-13 and fatty acid analysis can help to analysis the ecology of mesopelagic fishes. Here, we analysed the fatty acid composition of mesopelagic fishes from the continental northern slope of the South China Sea (NSSCS) and compared with nearshore SCS fishes and mesopelagic fishes collected from the Southern Ocean. The mesopelagic fishes had unusually high lipids, which resulted in Delta delta C-13 values exceeding 1 parts per thousand, more than the enrichment factor in the food web. The mesopelagic fishes had higher C18:1n-9/C18:1n-7 and C20:1n-9/ C18:1n-7 ratios compared with other fishes in the SCS, which confirmed that plankton were their main dietary source. The mesopelagic fishes from SCS and Southern Ocean had different ratios of C20:5n-3/C22:6n-3 (EPA/DHA), suggesting geographical locations and diet sources had obvious influence on their fatty acid composition. The SCS mesopelagic fishes had higher C20:4n-6/C22:6n-3 (ARA/DHA) and C20:4n-6/C20:5n-3 (ARA/EPA) ratios than mesopelagic fishes in the Southern Ocean, indicating the influence of physical factors on fatty acid composition. Thus, future studies of the fatty acids in mesopelagic fishes should consider both dietary sources and physical environments.