biostudies-literatureUnknown12Canseco JAQuantifying the tropic position (TP) of an animal species is key to understanding its ecosystem function. While both bulk and compound-specific analyses of stable isotopes are widely used for this purpose, few studies have assessed the consistency between and within such approaches. <i>Champsocephalus gunnari</i> is a specialist teleost that predates almost exclusively on Antarctic krill <i>Euphausia superba</i>. This well-known and nearly constant trophic relationship makes <i>C. gunnari</i> particularly suitable for assessing consistency between TP methods under field conditions. In the present work, we produced and compared TP estimates for <i>C. gunnari</i> and its main prey using a standard bulk and two amino acid-specific stable isotope approaches (CSI-AA). One based on the differencPeerJe17372https://www.ebi.ac.uk/biostudies/studies/S-EPMC11104342biostudies-literatureComparing trophic position estimates using bulk and compound specific stable isotope analyses: applying new approaches to mackerel icefish <i>Champsocephalus gunnari</i>.PMC11104342Harrod CQuezada-Romegialli CNiklitschek EJCanseco JAYarnes CfalseComparing trophic position estimates using bulk and compound specific stable isotope analyses: applying new approaches to mackerel icefish <i>Champsocephalus gunnari</i>.Quantifying the tropic position (TP) of an animal species is key to understanding its ecosystem function. While both bulk and compound-specific analyses of stable isotopes are widely used for this purpose, few studies have assessed the consistency between and within such approaches. <i>Champsocephalus gunnari</i> is a specialist teleost that predates almost exclusively on Antarctic krill <i>Euphausia superba</i>. This well-known and nearly constant trophic relationship makes <i>C. gunnari</i> particularly suitable for assessing consistency between TP methods under field conditions. In the present work, we produced and compared TP estimates for <i>C. gunnari</i> and its main prey using a standard bulk and two amino acid-specific stable isotope approaches (CSI-AA). One based on the differenc2024-01-01T00:00:00Z20242026-04-07T13:27:46.57Z2026-04-07T13:17:54.332ZS-EPMC111043423877009610.7717/peerj.17372