Lipids of Antarctic Ocean amphipods: food chain interactions and the occurrence of novel biomarkers

Abstract

Listen

Translate article

Antarctic hyperiid (Themisto gaudichaudi, Hyperia macrocephalus, and Primno macropa) and gammarid amphipods (Eusirus perdentatus and Orchomene rossi) were collected near Elephant Island, located in the South Shetland Islands, during January and February 1997 and 1998. Polar lipid (PL) was the major lipid class in all amphipods (58–88% of total lipid), except for T. gaudichaudi in which triacylglycerol (TAG) was dominant (62%). Cholesterol was the major sterol in the gammarid amphipods (89–91% of total sterols), and the hyperiid P. macropa (70%). The hyperiids T. gaudichaudi and H. macrocephalus had a more diverse sterol composition including trans-dehydrocholesterol, desmosterol, 24-nordehydrocholesterol, 24-methylcholest-5,22E-dien-3β-ol, 24-methylenecholesterol, and stanols (mostly cholestanol). Eicosapentaenoic acid [EPA, 20:5(n−3)] and docosahexaenoic acid [DHA, 22:6(n−3)] were the major polyunsaturated fatty acids (PUFA) in all amphipods. The PUFA octadecapentaenoic acid [18:5(n−3)] was not detected in 1997 samples, but comprised 0.3–1.2% in all 1998 samples. The PUFA 18:4(n−3) comprised 0.2–4.2% in all samples from both years. Very long chain PUFA (VLC-PUFA) (C24 and C26) were not detected in the one 1997 sample but comprised 0.6–2.8% of total fatty acids in almost all 1998 amphipods. Monounsaturated fatty acids included 18:1(n−9)c, 18:1(n−7)c, and 16:1(n−7)c. Principal saturated fatty acids in all amphipods were 16:0, 14:0, and 18:0. Examination of biomarker lipids has helped clarify trophic interactions for these Antarctic amphipods, and revealed annual differences in their food sources.