Determination of precise nitrogen stable isotopic baselines from heterotrophic organism in coastal ocean environments using compound specific isotope analysis of amino acids

• Published in: Marine pollution bulletin Vol. 171; p. 112777
• Main Authors: Choi, Bohyung, Shin, Kyung-Hoon
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.10.2021; Elsevier BV
• Subjects: Amino acids; CSIA of amino acids; Herbivores; Heterotrophic organisms; Isotope ratios; Isotopes; Isotopic baseline; Marine environment; Marine molluscs; Mollusks; Mussels; Nitrogen; Nitrogen isotope; Nitrogen isotopes; Nitrogen sources; Phenylalanine; Spatial variations; Trophic position; CSIA of amino acids; Isotopic baseline; Trophic position; Nitrogen isotope
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2021.112777

We sampled mussels (Mytilus edulis) along the coast of the Korean peninsula, and determined their trophic position (TP) using the nitrogen isotope ratio of amino acids (TPglu/phe). The TPglu/phe of mussels (2.0 to 2.5) is higher than TP of herbivores, suggesting that TP normalization is required to remove the trophic enrichment effect on basal nitrogen isotope ratio. We found similar trends in spatial variation between nitrogen isotopic baseline based on nitrogen isotope ratio of bulk tissue (δ15Nbase-bulk) and that of phenylalanine (δ15Nbase-phe) in mussels, reflecting different nitrogen sources among sampling sites. The present study suggests that δ15Nbase-bulk and δ15Nbase-phe are powerful tools to trace nitrogen isotopic baselines from primary consumers as well as higher TP organisms. •Nitrogen isotopic baselines were determined from the bulk tissue (15Nbase-bulk) and phenylalanine (δ15Nbase-phe) of mussels.•Temporal and spatial variations in δ15Nbase-bulk and δ15Nbase-phe reflect different nitrogen sources in estuaries in coastal waters.•Differences between the two nitrogen isotopic baselines are likely due to the uncertainty in the offset between the nitrogen isotope ratio of phenylalanine and the bulk tissue of the primary producer.